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TCSH(1)                                                                TCSH(1)

       tcsh - C shell with file name completion and command line editing

       tcsh [-bcdefFimnqstvVxX] [-Dname[=value]] [arg ...]
       tcsh -l

       tcsh is an enhanced but completely compatible version of the Berkeley UNIX C shell,
       csh(1).  It is a command language interpreter usable both as an  interactive  login
       shell and a shell script command processor.  It includes a command-line editor (see
       The command-line editor), programmable word completion (see  Completion  and  list-
       ing),  spelling correction (see Spelling correction), a history mechanism (see His-
       tory substitution), job control (see Jobs) and a C-like syntax.  The  NEW  FEATURES
       section  describes major enhancements of tcsh over csh(1).  Throughout this manual,
       features of tcsh not found in most csh(1) implementations (specifically, the 4.4BSD
       csh)  are labeled with '(+)', and features which are present in csh(1) but not usu-
       ally documented are labeled with '(u)'.

   Argument list processing
       If the first argument (argument 0) to the shell is '-' then it is a login shell.  A
       login  shell  can  be  also specified by invoking the shell with the -l flag as the
       only argument.

       The rest of the flag arguments are interpreted as follows:

       -b  Forces a ''break'' from option processing, causing any further shell  arguments
           to  be  treated  as  non-option arguments.  The remaining arguments will not be
           interpreted as shell options.  This may be used to  pass  options  to  a  shell
           script without confusion or possible subterfuge.  The shell will not run a set-
           user ID script without this option.

       -c  Commands are read from the following argument (which must be present, and  must
           be  a single argument), stored in the command shell variable for reference, and
           executed.  Any remaining arguments are placed in the argv shell variable.

       -d  The shell loads the directory stack from ~/.cshdirs as described under  Startup
           and shutdown, whether or not it is a login shell. (+)

           Sets the environment variable name to value. (Domain/OS only) (+)

       -e  The  shell  exits if any invoked command terminates abnormally or yields a non-
           zero exit status.

       -f  The shell does not load any resource or startup files, or perform  any  command
           hashing, and thus starts faster.

       -F  The shell uses fork(2) instead of vfork(2) to spawn processes. (+)

       -i  The  shell  is  interactive  and  prompts  for  its top-level input, even if it
           appears to not be a terminal.  Shells are interactive without  this  option  if
           their inputs and outputs are terminals.

       -l  The  shell is a login shell.  Applicable only if -l is the only flag specified.

       -m  The shell loads ~/.tcshrc even if it does not belong  to  the  effective  user.
           Newer versions of su(1) can pass -m to the shell. (+)

       -n  The  shell  parses  commands but does not execute them.  This aids in debugging
           shell scripts.

       -q  The shell accepts SIGQUIT (see Signal handling) and behaves  when  it  is  used
           under a debugger.  Job control is disabled. (u)

       -s  Command input is taken from the standard input.

       -t  The  shell  reads  and  executes  a single line of input.  A '\' may be used to
           escape the newline at the end of this line and continue onto another line.

       -v  Sets the verbose shell variable, so that command input is echoed after  history

       -x  Sets  the  echo  shell variable, so that commands are echoed immediately before

       -V  Sets the verbose shell variable even before executing ~/.tcshrc.

       -X  Is to -x as -V is to -v.

           Print a help message on the standard output and exit. (+)

           Print the version/platform/compilation options on the standard output and exit.
           This information is also contained in the version shell variable. (+)

       After processing of flag arguments, if arguments remain but none of the -c, -i, -s,
       or -t options were given, the first argument is taken as the name of a file of com-
       mands, or ''script'', to be executed.  The shell opens this file and saves its name
       for possible resubstitution by '$0'.  Because many systems use either the  standard
       version  6  or  version  7  shells whose shell scripts are not compatible with this
       shell, the shell uses such a 'standard' shell to execute a script whose first char-
       acter is not a '#', i.e., that does not start with a comment.

       Remaining arguments are placed in the argv shell variable.

   Startup and shutdown
       A login shell begins by executing commands from the system files /etc/csh.cshrc and
       /etc/csh.login.  It then executes commands from files in the user's home directory:
       first  ~/.tcshrc  (+)  or, if ~/.tcshrc is not found, ~/.cshrc, then ~/.history (or
       the value of the histfile shell variable), then ~/.login,  and  finally  ~/.cshdirs
       (or   the  value  of  the  dirsfile  shell  variable)  (+).   The  shell  may  read
       /etc/csh.login before instead of after /etc/csh.cshrc, and ~/.login before  instead
       of  after  ~/.tcshrc  or  ~/.cshrc  and ~/.history, if so compiled; see the version
       shell variable. (+)

       Non-login shells read only /etc/csh.cshrc and ~/.tcshrc or ~/.cshrc on startup.

       For examples of startup files, please consult

       Commands like stty(1) and tset(1), which need be run only once per  login,  usually
       go  in  one's ~/.login file.  Users who need to use the same set of files with both
       csh(1) and tcsh can have only a ~/.cshrc which checks for the existence of the tcsh
       shell  variable  (q.v.)  before  using  tcsh-specific  commands, or can have both a
       ~/.cshrc and a ~/.tcshrc which sources (see the  builtin  command)  ~/.cshrc.   The
       rest  of  this  manual  uses '~/.tcshrc' to mean '~/.tcshrc or, if ~/.tcshrc is not
       found, ~/.cshrc'.

       In the normal case, the shell begins reading commands from the terminal,  prompting
       with '> '.  (Processing of arguments and the use of the shell to process files con-
       taining command scripts are described later.)  The shell repeatedly reads a line of
       command  input, breaks it into words, places it on the command history list, parses
       it and executes each command in the line.

       One can log out by typing '^D' on an empty line, 'logout' or  'login'  or  via  the
       shell's  autologout  mechanism  (see  the autologout shell variable).  When a login
       shell terminates it sets the logout shell variable to 'normal'  or  'automatic'  as
       appropriate,  then  executes commands from the files /etc/csh.logout and ~/.logout.
       The shell may drop DTR on logout if so compiled; see the version shell variable.

       The names of the system login and logout files vary from system to system for  com-
       patibility with different csh(1) variants; see FILES.

       We first describe The command-line editor.  The Completion and listing and Spelling
       correction sections describe two sets of functionality that are implemented as edi-
       tor commands but which deserve their own treatment.  Finally, Editor commands lists
       and describes the editor commands specific to the shell and their default bindings.

   The command-line editor (+)
       Command-line  input  can  be edited using key sequences much like those used in GNU
       Emacs or vi(1).  The editor is active only when the edit  shell  variable  is  set,
       which  it is by default in interactive shells.  The bindkey builtin can display and
       change key bindings.  Emacs-style key bindings are  used  by  default  (unless  the
       shell  was  compiled  otherwise;  see  the version shell variable), but bindkey can
       change the key bindings to vi-style bindings en masse.

       The shell always binds the arrow keys (as defined in the TERMCAP environment  vari-
       able) to

           down    down-history
           up      up-history
           left    backward-char
           right   forward-char

       unless  doing  so  would  alter  another single-character binding.  One can set the
       arrow key escape sequences to the empty string with settc to  prevent  these  bind-
       ings.  The ANSI/VT100 sequences for arrow keys are always bound.

       Other  key bindings are, for the most part, what Emacs and vi(1) users would expect
       and can easily be displayed by bindkey, so there is no  need  to  list  them  here.
       Likewise, bindkey can list the editor commands with a short description of each.

       Note  that  editor  commands  do not have the same notion of a ''word'' as does the
       shell.  The editor delimits words with any non-alphanumeric characters not  in  the
       shell  variable  wordchars,  while the shell recognizes only whitespace and some of
       the characters with special meanings to it, listed under Lexical structure.

   Completion and listing (+)
       The shell is often able to complete words when given a unique  abbreviation.   Type
       part  of  a  word  (for example 'ls /usr/lost') and hit the tab key to run the com-
       plete-word editor  command.   The  shell  completes  the  filename  '/usr/lost'  to
       '/usr/lost+found/',  replacing  the  incomplete  word with the complete word in the
       input buffer.  (Note the terminal '/'; completion adds a '/' to  the  end  of  com-
       pleted directories and a space to the end of other completed words, to speed typing
       and provide a visual indicator of successful completion.  The addsuffix shell vari-
       able   can   be   unset   to   prevent  this.)   If  no  match  is  found  (perhaps
       '/usr/lost+found' doesn't exist), the terminal bell rings.  If the word is  already
       complete (perhaps there is a '/usr/lost' on your system, or perhaps you were think-
       ing too far ahead and typed the whole thing) a '/' or space is added to the end  if
       it isn't already there.

       Completion  works  anywhere in the line, not at just the end; completed text pushes
       the rest of the line to the right.  Completion  in  the  middle  of  a  word  often
       results  in leftover characters to the right of the cursor that need to be deleted.

       Commands and variables can be completed in much the same way.  For example,  typing
       'em[tab]'  would  complete  'em'  to 'emacs' if emacs were the only command on your
       system beginning with 'em'.  Completion can find a command in any directory in path
       or  if  given  a  full  pathname.   Typing  'echo $ar[tab]' would complete '$ar' to
       '$argv' if no other variable began with 'ar'.

       The shell parses the input buffer  to  determine  whether  the  word  you  want  to
       complete should be completed as a filename, command or variable.  The first word in
       the buffer and the first word following ';', '|', '|&', '&&' or '||' is  considered
       to  be  a command.  A word beginning with '$' is considered to be a variable.  Any-
       thing else is a filename.  An empty line is 'completed' as a filename.

       You can list the possible completions of a word at any time by typing '^D'  to  run
       the  delete-char-or-list-or-eof  editor command.  The shell lists the possible com-
       pletions using the ls-F builtin (q.v.)  and reprints the prompt and unfinished com-
       mand line, for example:

           > ls /usr/l[^D]
           lbin/       lib/        local/      lost+found/
           > ls /usr/l

       If  the  autolist  shell variable is set, the shell lists the remaining choices (if
       any) whenever completion fails:

           > set autolist
           > nm /usr/lib/libt[tab]
           libtermcap.a@ libtermlib.a@
           > nm /usr/lib/libterm

       If autolist is set to 'ambiguous', choices are listed only  when  completion  fails
       and adds no new characters to the word being completed.

       A filename to be completed can contain variables, your own or others' home directo-
       ries abbreviated with '~' (see Filename substitution) and directory  stack  entries
       abbreviated with '=' (see Directory stack substitution).  For example,

           > ls ~k[^D]
           kahn    kas     kellogg
           > ls ~ke[tab]
           > ls ~kellogg/


           > set local = /usr/local
           > ls $lo[tab]
           > ls $local/[^D]
           bin/ etc/ lib/ man/ src/
           > ls $local/

       Note  that variables can also be expanded explicitly with the expand-variables edi-
       tor command.

       delete-char-or-list-or-eof lists at only the end of the line; in the  middle  of  a
       line it deletes the character under the cursor and on an empty line it logs one out
       or, if ignoreeof is set, does nothing.  'M-^D', bound to the editor  command  list-
       choices,  lists  completion  possibilities anywhere on a line, and list-choices (or
       any one of the related editor commands that do or don't  delete,  list  and/or  log
       out, listed under delete-char-or-list-or-eof) can be bound to '^D' with the bindkey
       builtin command if so desired.

       The complete-word-fwd and complete-word-back editor commands (not bound to any keys
       by  default)  can be used to cycle up and down through the list of possible comple-
       tions, replacing the current word with the next or previous word in the list.

       The shell variable fignore can be set to a list of suffixes to be ignored  by  com-
       pletion.  Consider the following:

           > ls
           Makefile        condiments.h~   main.o          side.c
           README          main.c          meal            side.o
           condiments.h    main.c~
           > set fignore = (.o \~)
           > emacs ma[^D]
           main.c   main.c~  main.o
           > emacs ma[tab]
           > emacs main.c

       'main.c~'  and  'main.o'  are ignored by completion (but not listing), because they
       end in suffixes in fignore.  Note that a '\' was needed in front of '~' to  prevent
       it  from  being expanded to home as described under Filename substitution.  fignore
       is ignored if only one completion is possible.

       If the complete shell variable is set to 'enhance', completion 1) ignores case  and
       2) considers periods, hyphens and underscores ('.', '-' and '_') to be word separa-
       tors and hyphens and underscores to be equivalent.  If you had the following files

           comp.lang.c      comp.lang.perl   comp.std.c++
           comp.lang.c++    comp.std.c

       and typed 'mail -f c.l.c[tab]', it would be completed to 'mail -f comp.lang.c', and
       ^D  would  list 'comp.lang.c' and 'comp.lang.c++'.  'mail -f c..c++[^D]' would list
       'comp.lang.c++' and 'comp.std.c++'.   Typing  'rm  a--file[^D]'  in  the  following

           A_silly_file    a-hyphenated-file    another_silly_file

       would list all three files, because case is ignored and hyphens and underscores are
       equivalent.  Periods, however, are not equivalent to hyphens or underscores.

       Completion and listing are affected by several other shell variables: recexact  can
       be set to complete on the shortest possible unique match, even if more typing might
       result in a longer match:

           > ls
           fodder   foo      food     foonly
           > set recexact
           > rm fo[tab]

       just beeps, because 'fo' could expand to 'fod' or 'foo', but  if  we  type  another

           > rm foo[tab]
           > rm foo

       the  completion  completes  on  'foo',  even though 'food' and 'foonly' also match.
       autoexpand can be set to run the expand-history editor command before each  comple-
       tion  attempt,  autocorrect can be set to spelling-correct the word to be completed
       (see Spelling correction) before each completion attempt and correct can be set  to
       complete  commands  automatically after one hits 'return'.  matchbeep can be set to
       make completion beep or not beep in a variety of situations, and nobeep can be  set
       to  never  beep at all.  nostat can be set to a list of directories and/or patterns
       that match directories to prevent the completion mechanism  from  stat(2)ing  those
       directories.   listmax  and listmaxrows can be set to limit the number of items and
       rows (respectively) that are listed without asking first.   recognize_only_executa-
       bles  can be set to make the shell list only executables when listing commands, but
       it is quite slow.

       Finally, the complete builtin command can be used to tell the shell how to complete
       words  other than filenames, commands and variables.  Completion and listing do not
       work on glob-patterns (see Filename substitution), but the  list-glob  and  expand-
       glob editor commands perform equivalent functions for glob-patterns.

   Spelling correction (+)
       The  shell  can  sometimes correct the spelling of filenames, commands and variable
       names as well as completing and listing them.

       Individual words can be spelling-corrected with the spell-word editor command (usu-
       ally  bound  to  M-s  and M-S) and the entire input buffer with spell-line (usually
       bound to M-$).  The correct shell variable can be  set  to  'cmd'  to  correct  the
       command  name  or  'all'  to correct the entire line each time return is typed, and
       autocorrect can be set to correct the word to be completed before  each  completion

       When  spelling correction is invoked in any of these ways and the shell thinks that
       any part of the command line is misspelled, it prompts with the corrected line:

           > set correct = cmd
           > lz /usr/bin
           CORRECT>ls /usr/bin (y|n|e|a)?

       One can answer 'y' or space to execute the corrected line, 'e' to leave the  uncor-
       rected  command  in  the input buffer, 'a' to abort the command as if '^C' had been
       hit, and anything else to execute the original line unchanged.

       Spelling correction recognizes user-defined completions (see the  complete  builtin
       command).   If an input word in a position for which a completion is defined resem-
       bles a word in the completion list, spelling correction registers a misspelling and
       suggests  the  latter  word  as  a correction.  However, if the input word does not
       match any of the possible completions for that position, spelling  correction  does
       not register a misspelling.

       Like  completion,  spelling correction works anywhere in the line, pushing the rest
       of the line to the right and possibly leaving extra characters to the right of  the

       Beware:  spelling  correction is not guaranteed to work the way one intends, and is
       provided mostly as an experimental feature.  Suggestions and improvements are  wel-

   Editor commands (+)
       'bindkey'  lists  key  bindings and 'bindkey -l' lists and briefly describes editor
       commands.  Only new or especially interesting editor commands are  described  here.
       See emacs(1) and vi(1) for descriptions of each editor's key bindings.

       The  character  or characters to which each command is bound by default is given in
       parentheses.  '^character' means a control character and 'M-character' a meta char-
       acter, typed as escape-character on terminals without a meta key.  Case counts, but
       commands that are bound to letters by default are bound to both lower-  and  upper-
       case letters for convenience.

       complete-word (tab)
               Completes a word as described under Completion and listing.

       complete-word-back (not bound)
               Like complete-word-fwd, but steps up from the end of the list.

       complete-word-fwd (not bound)
               Replaces  the current word with the first word in the list of possible com-
               pletions.  May be repeated to step down through the list.  At  the  end  of
               the list, beeps and reverts to the incomplete word.

       complete-word-raw (^X-tab)
               Like complete-word, but ignores user-defined completions.

       copy-prev-word (M-^_)
               Copies  the  previous  word in the current line into the input buffer.  See
               also insert-last-word.

       dabbrev-expand (M-/)
               Expands the current word to the most recent preceding  one  for  which  the
               current  is a leading substring, wrapping around the history list (once) if
               necessary.  Repeating dabbrev-expand without any intervening typing changes
               to  the  next previous word etc., skipping identical matches much like his-
               tory-search-backward does.

       delete-char (not bound)
               Deletes the character under the cursor.  See  also  delete-char-or-list-or-

       delete-char-or-eof (not bound)
               Does delete-char if there is a character under the cursor or end-of-file on
               an empty line.  See also delete-char-or-list-or-eof.

       delete-char-or-list (not bound)
               Does delete-char if there is a character under the cursor  or  list-choices
               at the end of the line.  See also delete-char-or-list-or-eof.

       delete-char-or-list-or-eof (^D)
               Does  delete-char if there is a character under the cursor, list-choices at
               the end of the line or end-of-file on an empty line.  See also those  three
               commands,  each of which does only a single action, and delete-char-or-eof,
               delete-char-or-list and list-or-eof, each of which does a different two out
               of the three.

       down-history (down-arrow, ^N)
               Like up-history, but steps down, stopping at the original input line.

       end-of-file (not bound)
               Signals  an  end  of  file,  causing the shell to exit unless the ignoreeof
               shell variable (q.v.) is set to prevent  this.   See  also  delete-char-or-

       expand-history (M-space)
               Expands  history  substitutions in the current word.  See History substitu-
               tion.  See also  magic-space,  toggle-literal-history  and  the  autoexpand
               shell variable.

       expand-glob (^X-*)
               Expands the glob-pattern to the left of the cursor.  See Filename substitu-

       expand-line (not bound)
               Like expand-history, but expands history substitutions in each word in  the
               input buffer,

       expand-variables (^X-$)
               Expands the variable to the left of the cursor.  See Variable substitution.

       history-search-backward (M-p, M-P)
               Searches backwards through the history list for a  command  beginning  with
               the  current  contents  of  the input buffer up to the cursor and copies it
               into the input buffer.  The search string may be a glob-pattern (see  File-
               name substitution) containing '*', '?', '[]' or '{}'.  up-history and down-
               history will proceed from the appropriate point in the history list.  Emacs
               mode only.  See also history-search-forward and i-search-back.

       history-search-forward (M-n, M-N)
               Like history-search-backward, but searches forward.

       i-search-back (not bound)
               Searches backward like history-search-backward, copies the first match into
               the input buffer with the cursor positioned at the end of the pattern,  and
               prompts  with  'bck:  '  and the first match.  Additional characters may be
               typed to extend the search, i-search-back may be typed to continue  search-
               ing  with  the same pattern, wrapping around the history list if necessary,
               (i-search-back must be bound to a single character for this to work) or one
               of the following special characters may be typed:

                   ^W      Appends  the  rest  of  the word under the cursor to the search
                   delete (or any character bound to backward-delete-char)
                           Undoes the effect of the last character  typed  and  deletes  a
                           character from the search pattern if appropriate.
                   ^G      If  the  previous  search  was  successful,  aborts  the entire
                           search.  If not, goes back to the last successful search.
                   escape  Ends the search, leaving the current line in the input  buffer.

               Any other character not bound to self-insert-command terminates the search,
               leaving the current line in the input buffer, and is  then  interpreted  as
               normal  input.  In particular, a carriage return causes the current line to
               be executed.  Emacs mode only.  See also i-search-fwd  and  history-search-

       i-search-fwd (not bound)
               Like i-search-back, but searches forward.

       insert-last-word (M-_)
               Inserts  the  last  word  of  the previous input line ('!$') into the input
               buffer.  See also copy-prev-word.

       list-choices (M-^D)
               Lists completion possibilities as described under Completion  and  listing.
               See also delete-char-or-list-or-eof and list-choices-raw.

       list-choices-raw (^X-^D)
               Like list-choices, but ignores user-defined completions.

       list-glob (^X-g, ^X-G)
               Lists (via the ls-F builtin) matches to the glob-pattern (see Filename sub-
               stitution) to the left of the cursor.

       list-or-eof (not bound)
               Does list-choices or end-of-file on an empty line.  See  also  delete-char-

       magic-space (not bound)
               Expands history substitutions in the current line, like expand-history, and
               inserts a space.  magic-space is designed to be bound to the space bar, but
               is not bound by default.

       normalize-command (^X-?)
               Searches for the current word in PATH and, if it is found, replaces it with
               the full path to the executable.  Special characters are  quoted.   Aliases
               are  expanded and quoted but commands within aliases are not.  This command
               is useful with commands that take commands as arguments,  e.g.,  'dbx'  and
               'sh -x'.

       normalize-path (^X-n, ^X-N)
               Expands  the  current  word  as described under the 'expand' setting of the
               symlinks shell variable.

       overwrite-mode (unbound)
               Toggles between input and overwrite modes.

       run-fg-editor (M-^Z)
               Saves the current input line and looks for a stopped job with a name  equal
               to  the  last component of the file name part of the EDITOR or VISUAL envi-
               ronment variables, or, if neither is set, 'ed' or 'vi'.  If such a  job  is
               found,  it  is  restarted  as if 'fg %job' had been typed.  This is used to
               toggle back and forth between an editor and the shell easily.  Some  people
               bind this command to '^Z' so they can do this even more easily.

       run-help (M-h, M-H)
               Searches for documentation on the current command, using the same notion of
               'current command' as the completion routines, and prints it.  There  is  no
               way to use a pager; run-help is designed for short help files.  If the spe-
               cial alias helpcommand is defined, it is run with the  command  name  as  a
               sole argument.  Else, documentation should be in a file named,
               command.1, command.6, command.8 or command, which should be in one  of  the
               directories  listed  in  the  HPATH environment variable.  If there is more
               than one help file only the first is printed.

       self-insert-command (text characters)
               In insert mode (the default), inserts the typed character  into  the  input
               line after the character under the cursor.  In overwrite mode, replaces the
               character under the cursor with the typed character.   The  input  mode  is
               normally  preserved  between lines, but the inputmode shell variable can be
               set to 'insert' or 'overwrite' to put the editor in that mode at the begin-
               ning of each line.  See also overwrite-mode.

       sequence-lead-in (arrow prefix, meta prefix, ^X)
               Indicates  that  the following characters are part of a multi-key sequence.
               Binding a command to a multi-key sequence really creates two bindings:  the
               first  character to sequence-lead-in and the whole sequence to the command.
               All sequences beginning with a  character  bound  to  sequence-lead-in  are
               effectively bound to undefined-key unless bound to another command.

       spell-line (M-$)
               Attempts  to  correct  the  spelling of each word in the input buffer, like
               spell-word, but ignores words whose first character is one of '-', '!', '^'
               or  '%', or which contain '\', '*' or '?', to avoid problems with switches,
               substitutions and the like.  See Spelling correction.

       spell-word (M-s, M-S)
               Attempts to correct the spelling of the current  word  as  described  under
               Spelling correction.  Checks each component of a word which appears to be a

       toggle-literal-history (M-r, M-R)
               Expands or 'unexpands' history substitutions in the input buffer.  See also
               expand-history and the autoexpand shell variable.

       undefined-key (any unbound key)

       up-history (up-arrow, ^P)
               Copies  the  previous  entry in the history list into the input buffer.  If
               histlit is set, uses the literal form of the entry.   May  be  repeated  to
               step up through the history list, stopping at the top.

       vi-search-back (?)
               Prompts  with '?' for a search string (which may be a glob-pattern, as with
               history-search-backward), searches for it and  copies  it  into  the  input
               buffer.   The  bell  rings  if  no match is found.  Hitting return ends the
               search and leaves the last match in the input buffer.  Hitting escape  ends
               the search and executes the match.  vi mode only.

       vi-search-fwd (/)
               Like vi-search-back, but searches forward.

       which-command (M-?)
               Does a which (see the description of the builtin command) on the first word
               of the input buffer.

       yank-pop (M-y)
               When executed immediately after a yank or another  yank-pop,  replaces  the
               yanked  string  with  the next previous string from the killring. This also
               has the effect of rotating the killring, such that this string will be con-
               sidered  the  most recently killed by a later yank command. Repeating yank-
               pop will cycle through the killring any number of times.

   Lexical structure
       The shell splits input lines into words at blanks and tabs.  The special characters
       '&',  '|',  ';', '<', '>', '(', and ')' and the doubled characters '&&', '||', '<<'
       and '>>' are always separate words, whether or not they are surrounded  by  whites-

       When  the  shell's  input  is not a terminal, the character '#' is taken to begin a
       comment.  Each '#' and the rest of the input line on which it appears is  discarded
       before further parsing.

       A  special  character  (including  a blank or tab) may be prevented from having its
       special meaning, and possibly made part of another word, by  preceding  it  with  a
       backslash  ('\')  or  enclosing  it in single ('''), double ('"') or backward (''')
       quotes.  When not otherwise quoted a newline preceded by a '\' is equivalent  to  a
       blank, but inside quotes this sequence results in a newline.

       Furthermore,  all Substitutions (see below) except History substitution can be pre-
       vented by enclosing the strings (or parts of strings) in  which  they  appear  with
       single quotes or by quoting the crucial character(s) (e.g., '$' or ''' for Variable
       substitution or Command substitution respectively) with '\'.   (Alias  substitution
       is  no exception: quoting in any way any character of a word for which an alias has
       been defined prevents substitution of the alias.  The usual way of quoting an alias
       is  to  precede  it  with  a backslash.) History substitution is prevented by back-
       slashes but not by single quotes.  Strings quoted with double  or  backward  quotes
       undergo Variable substitution and Command substitution, but other substitutions are

       Text inside single or double quotes  becomes  a  single  word  (or  part  of  one).
       Metacharacters  in  these  strings, including blanks and tabs, do not form separate
       words.  Only in one special case (see Command substitution  below)  can  a  double-
       quoted  string  yield  parts of more than one word; single-quoted strings never do.
       Backward quotes are special: they signal Command  substitution  (q.v.),  which  may
       result in more than one word.

       Quoting  complex  strings,  particularly  strings  which themselves contain quoting
       characters, can be confusing.  Remember that quotes need not be used as they are in
       human  writing!   It  may  be  easier to quote not an entire string, but only those
       parts of the string which need quoting, using different types of quoting to  do  so
       if appropriate.

       The  backslash_quote  shell  variable  (q.v.) can be set to make backslashes always
       quote '\', ''', and '"'.  (+) This may make complex quoting tasks  easier,  but  it
       can cause syntax errors in csh(1) scripts.

       We  now describe the various transformations the shell performs on the input in the
       order in which they occur.  We note in passing the data structures involved and the
       commands  and variables which affect them.  Remember that substitutions can be pre-
       vented by quoting as described under Lexical structure.

   History substitution
       Each command, or ''event'', input from the terminal is saved in the  history  list.
       The  previous command is always saved, and the history shell variable can be set to
       a number to save that many commands.  The histdup shell variable can be set to  not
       save duplicate events or consecutive duplicate events.

       Saved  commands  are numbered sequentially from 1 and stamped with the time.  It is
       not usually necessary to use event numbers, but the current  event  number  can  be
       made part of the prompt by placing an '!' in the prompt shell variable.

       The  shell  actually  saves history in expanded and literal (unexpanded) forms.  If
       the histlit shell variable is set, commands that display and store history use  the
       literal form.

       The  history builtin command can print, store in a file, restore and clear the his-
       tory list at any time, and the savehist and histfile shell variables can be can  be
       set to store the history list automatically on logout and restore it on login.

       History  substitutions introduce words from the history list into the input stream,
       making it easy to repeat commands, repeat arguments of a previous  command  in  the
       current  command, or fix spelling mistakes in the previous command with little typ-
       ing and a high degree of confidence.

       History substitutions begin with the character '!'.  They may begin anywhere in the
       input  stream,  but  they do not nest.  The '!' may be preceded by a '\' to prevent
       its special meaning; for convenience, a '!' is passed unchanged when it is followed
       by  a  blank,  tab,  newline, '=' or '('.  History substitutions also occur when an
       input line begins with '^'.  This special abbreviation  will  be  described  later.
       The  characters used to signal history substitution ('!' and '^') can be changed by
       setting the histchars shell variable.  Any input line which contains a history sub-
       stitution is printed before it is executed.

       A  history  substitution  may  have an ''event specification'', which indicates the
       event from which words are to be taken, a ''word designator'', which  selects  par-
       ticular  words  from the chosen event, and/or a ''modifier'', which manipulates the
       selected words.

       An event specification can be

           n       A number, referring to a particular event
           -n      An offset, referring to the event n before the current event
           #       The current event.  This should be  used  carefully  in  csh(1),  where
                   there  is  no check for recursion.  tcsh allows 10 levels of recursion.
           !       The previous event (equivalent to '-1')
           s       The most recent event whose first word begins with the string s
           ?s?     The most recent event which contains the string s.  The second '?'  can
                   be omitted if it is immediately followed by a newline.

       For example, consider this bit of someone's history list:

            9  8:30    nroff -man
           10  8:31    cp
           11  8:36    vi
           12  8:37    diff

       The  commands  are  shown  with  their  event numbers and time stamps.  The current
       event, which we haven't typed in yet, is event 13.  '!11' and '!-2' refer to  event
       11.   '!!'  refers to the previous event, 12.  '!!' can be abbreviated '!' if it is
       followed by ':' (':' is described below).  '!n' refers to  event  9,  which  begins
       with  'n'.   '!?old?'  also refers to event 12, which contains 'old'.  Without word
       designators or modifiers history references simply expand to the entire  event,  so
       we  might  type  '!cp'  to  redo the copy command or '!!|more' if the 'diff' output
       scrolled off the top of the screen.

       History references may be insulated from the surrounding text with braces if neces-
       sary.  For example, '!vdoc' would look for a command beginning with 'vdoc', and, in
       this example, not find one, but '!{v}doc' would expand unambiguously  to  'vi  wum-
       pus.mandoc'.  Even in braces, history substitutions do not nest.

       (+)  While  csh(1)  expands,  for  example,  '!3d'  to  event 3 with the letter 'd'
       appended to it, tcsh expands it to the last event beginning with  '3d';  only  com-
       pletely  numeric arguments are treated as event numbers.  This makes it possible to
       recall events beginning with numbers.  To expand '!3d' as in csh(1) say '!{3}d'.

       To select words from an event we can follow the event specification by a ':' and  a
       designator  for the desired words.  The words of an input line are numbered from 0,
       the first (usually command) word being 0, the second word (first argument) being 1,
       etc.  The basic word designators are:

           0       The first (command) word
           n       The nth argument
           ^       The first argument, equivalent to '1'
           $       The last argument
           %       The word matched by an ?s? search
           x-y     A range of words
           -y      Equivalent to '0-y'
           *       Equivalent  to  '^-$', but returns nothing if the event contains only 1
           x*      Equivalent to 'x-$'
           x-      Equivalent to 'x*', but omitting the last word ('$')

       Selected words are inserted into the command line separated by single blanks.   For
       example,  the 'diff' command in the previous example might have been typed as 'diff
       !!:1.old !!:1' (using ':1' to select the first argument from the previous event) or
       'diff  !-2:2  !-2:1' to select and swap the arguments from the 'cp' command.  If we
       didn't care about the order of the 'diff' we might have said 'diff !-2:1-2' or sim-
       ply  'diff  !-2:*'.   The  'cp'  command  might  have  been  written 'cp
       !#:1.old', using '#' to refer to the current event.  '!n:-' would  reuse
       the first two words from the 'nroff' command to say 'nroff -man'.

       The  ':' separating the event specification from the word designator can be omitted
       if the argument selector begins with a '^', '$', '*', '%' or '-'.  For example, our
       'diff'  command  might have been 'diff !!^.old !!^' or, equivalently, 'diff !!$.old
       !!$'.  However, if '!!' is abbreviated '!', an argument selector beginning with '-'
       will be interpreted as an event specification.

       A history reference may have a word designator but no event specification.  It then
       references the previous command.  Continuing our 'diff' example, we could have said
       simply  'diff !^.old !^' or, to get the arguments in the opposite order, just 'diff

       The word or words in a history reference can be edited, or ''modified'', by follow-
       ing it with one or more modifiers, each preceded by a ':':

           h       Remove a trailing pathname component, leaving the head.
           t       Remove all leading pathname components, leaving the tail.
           r       Remove a filename extension '.xxx', leaving the root name.
           e       Remove all but the extension.
           u       Uppercase the first lowercase letter.
           l       Lowercase the first uppercase letter.
           s/l/r/  Substitute l for r.  l is simply a string like r, not a regular expres-
                   sion as in the eponymous ed(1) command.  Any character may be  used  as
                   the delimiter in place of '/'; a '\' can be used to quote the delimiter
                   expect '(', ')', '|' and '>' inside l and r.  The character '&' in  the
                   r  is  replaced by l; '\' also quotes '&'.  If l is empty (''''), the l
                   from a previous substitution or the s from a previous search  or  event
                   number  in  event specification is used.  The trailing delimiter may be
                   omitted if it is immediately followed by a newline.
           &       Repeat the previous substitution.
           g       Apply the following modifier once to each word.
           a (+)   Apply the following modifier as many times  as  possible  to  a  single
                   word.   'a'  and 'g' can be used together to apply a modifier globally.
                   With the 's' modifier, only the patterns contained in the original word
                   are substituted, not patterns that contain any substitution result.
           p       Print the new command line but do not execute it.
           q       Quote the substituted words, preventing further substitutions.
           x       Like q, but break into words at blanks, tabs and newlines.

       Modifiers  are  applied to only the first modifiable word (unless 'g' is used).  It
       is an error for no word to be modifiable.

       For example, the 'diff' command might have been  written  as  'diff
       !#^:r',  using  ':r'  to  remove  '.old'  from  the first argument on the same line
       ('!#^').  We could say 'echo hello out  there',  then  'echo  !*:u'  to  capitalize
       'hello',  'echo  !*:au'  to  say it out loud, or 'echo !*:agu' to really shout.  We
       might follow 'mail -s "I forgot my password" rot' with  '!:s/rot/root'  to  correct
       the spelling of 'root' (but see Spelling correction for a different approach).

       There is a special abbreviation for substitutions.  '^', when it is the first char-
       acter on an input  line,  is  equivalent  to  '!:s^'.   Thus  we  might  have  said
       '^rot^root'  to  make the spelling correction in the previous example.  This is the
       only history substitution which does not explicitly begin with '!'.

       (+) In csh as such, only one modifier may be applied to each  history  or  variable
       expansion.  In tcsh, more than one may be used, for example

           % mv /usr/man/man1/wumpus.1
           % man !$:t:r
           man wumpus

       In  csh,  the result would be 'wumpus.1:r'.  A substitution followed by a colon may
       need to be insulated from it with braces:

           > mv a.out /usr/games/wumpus
           > setenv PATH !$:h:$PATH
           Bad ! modifier: $.
           > setenv PATH !{-2$:h}:$PATH
           setenv PATH /usr/games:/bin:/usr/bin:.

       The first attempt would succeed in csh but fails  in  tcsh,  because  tcsh  expects
       another modifier after the second colon rather than '$'.

       Finally,  history can be accessed through the editor as well as through the substi-
       tutions just described.  The  up-  and  down-history,  history-search-backward  and
       -forward,  i-search-back  and  -fwd,  vi-search-back  and  -fwd, copy-prev-word and
       insert-last-word editor commands search for events in the  history  list  and  copy
       them  into  the  input  buffer.  The toggle-literal-history editor command switches
       between the expanded and literal forms  of  history  lines  in  the  input  buffer.
       expand-history and expand-line expand history substitutions in the current word and
       in the entire input buffer respectively.

   Alias substitution
       The shell maintains a list of aliases which can be set, unset and  printed  by  the
       alias  and  unalias  commands.  After a command line is parsed into simple commands
       (see Commands) the first word of each command, left-to-right, is checked to see  if
       it  has  an  alias.   If so, the first word is replaced by the alias.  If the alias
       contains a history reference, it undergoes History substitution  (q.v.)  as  though
       the original command were the previous input line.  If the alias does not contain a
       history reference, the argument list is left untouched.

       Thus if the alias for 'ls' were 'ls -l' the command 'ls /usr' would become  'ls  -l
       /usr',  the  argument  list here being undisturbed.  If the alias for 'lookup' were
       'grep !^ /etc/passwd' then 'lookup bill'  would  become  'grep  bill  /etc/passwd'.
       Aliases  can be used to introduce parser metasyntax.  For example, 'alias print 'pr
       \!* | lpr'' defines a ''command'' ('print') which pr(1)s its arguments to the  line

       Alias  substitution  is  repeated until the first word of the command has no alias.
       If an alias substitution does not change the first word (as in the  previous  exam-
       ple) it is flagged to prevent a loop.  Other loops are detected and cause an error.

       Some aliases are referred to by the shell; see Special aliases.

   Variable substitution
       The shell maintains a list of variables, each of which has as value a list of  zero
       or more words.  The values of shell variables can be displayed and changed with the
       set and unset commands.  The system maintains its own list of ''environment'' vari-
       ables.  These can be displayed and changed with printenv, setenv and unsetenv.

       (+)  Variables  may be made read-only with 'set -r' (q.v.)  Read-only variables may
       not be modified or unset; attempting to do so will cause an error.  Once made read-
       only,  a variable cannot be made writable, so 'set -r' should be used with caution.
       Environment variables cannot be made read-only.

       Some variables are set by the shell or referred to by it.  For instance,  the  argv
       variable  is  an  image  of the shell's argument list, and words of this variable's
       value are referred to in special ways.  Some of the variables referred  to  by  the
       shell  are  toggles; the shell does not care what their value is, only whether they
       are set or not.  For instance, the verbose variable is a toggle which  causes  com-
       mand  input  to be echoed.  The -v command line option sets this variable.  Special
       shell variables lists all variables which are referred to by the shell.

       Other operations treat variables numerically.  The '@' command permits numeric cal-
       culations  to  be performed and the result assigned to a variable.  Variable values
       are, however, always represented as (zero or more) strings.  For  the  purposes  of
       numeric  operations,  the  null string is considered to be zero, and the second and
       subsequent words of multi-word values are ignored.

       After the input line is aliased and parsed, and before each  command  is  executed,
       variable  substitution is performed keyed by '$' characters.  This expansion can be
       prevented by preceding the '$' with a  '\'  except  within  '"'s  where  it  always
       occurs,  and  within  '''s where it never occurs.  Strings quoted by ''' are inter-
       preted later (see Command substitution below) so '$' substitution  does  not  occur
       there  until  later,  if at all.  A '$' is passed unchanged if followed by a blank,
       tab, or end-of-line.

       Input/output redirections are recognized before variable expansion, and  are  vari-
       able expanded separately.  Otherwise, the command name and entire argument list are
       expanded together.  It is thus possible for  the  first  (command)  word  (to  this
       point) to generate more than one word, the first of which becomes the command name,
       and the rest of which become arguments.

       Unless enclosed in '"' or given the ':q' modifier the results of variable substitu-
       tion  may  eventually  be command and filename substituted.  Within '"', a variable
       whose value consists of multiple words expands to a (portion  of  a)  single  word,
       with the words of the variable's value separated by blanks.  When the ':q' modifier
       is applied to a substitution the variable will expand to multiple words  with  each
       word separated by a blank and quoted to prevent later command or filename substitu-

       The following metasequences are provided for introducing variable values  into  the
       shell  input.  Except as noted, it is an error to reference a variable which is not

       ${name} Substitutes the words of the value of variable name, each  separated  by  a
               blank.   Braces  insulate name from following characters which would other-
               wise be part of it.  Shell variables have names consisting of  letters  and
               digits  starting  with  a letter.  The underscore character is considered a
               letter.  If name is not a shell variable, but is set  in  the  environment,
               then  that  value  is returned (but some of the other forms given below are
               not available in this case).
               Substitutes only the selected words from the value of name.   The  selector
               is  subjected to '$' substitution and may consist of a single number or two
               numbers separated by a '-'.  The first word of a variable's value  is  num-
               bered  '1'.   If the first number of a range is omitted it defaults to '1'.
               If the last member of a range is omitted  it  defaults  to  '$#name'.   The
               selector '*' selects all words.  It is not an error for a range to be empty
               if the second argument is omitted or in range.
       $0      Substitutes the name of the file from which command input  is  being  read.
               An error occurs if the name is not known.
               Equivalent to '$argv[number]'.
       $*      Equivalent to '$argv', which is equivalent to '$argv[*]'.

       The  ':'  modifiers  described  under History substitution, except for ':p', can be
       applied to the substitutions above.  More than one may be used.  (+) Braces may  be
       needed  to  insulate a variable substitution from a literal colon just as with His-
       tory substitution (q.v.); any modifiers must appear within the braces.

       The following substitutions can not be modified with ':' modifiers.

               Substitutes the string '1' if name is set, '0' if it is not.
       $?0     Substitutes '1' if the current input filename is known, '0' if it  is  not.
               Always '0' in interactive shells.
               Substitutes the number of words in name.
       $#      Equivalent to '$#argv'.  (+)
               Substitutes the number of characters in name.  (+)
               Substitutes the number of characters in $argv[number].  (+)
       $?      Equivalent to '$status'.  (+)
       $$      Substitutes the (decimal) process number of the (parent) shell.
       $!      Substitutes  the  (decimal)  process  number of the last background process
               started by this shell.  (+)
       $_      Substitutes the command line of the last command executed.  (+)
       $<      Substitutes a line from the standard input, with no further  interpretation
               thereafter.   It  can  be used to read from the keyboard in a shell script.
               (+) While csh always quotes $<, as if it were equivalent  to  '$<:q',  tcsh
               does  not.   Furthermore,  when  tcsh is waiting for a line to be typed the
               user may type an interrupt to interrupt the sequence into which the line is
               to be substituted, but csh does not allow this.

       The  editor  command  expand-variables,  normally  bound  to '^X-$', can be used to
       interactively expand individual variables.

   Command, filename and directory stack substitution
       The remaining substitutions are applied selectively to  the  arguments  of  builtin
       commands.   This means that portions of expressions which are not evaluated are not
       subjected to these expansions.  For commands which are not internal to  the  shell,
       the  command  name  is  substituted separately from the argument list.  This occurs
       very late, after input-output redirection is performed, and in a child of the  main

   Command substitution
       Command  substitution  is  indicated by a command enclosed in '''.  The output from
       such a command is broken into separate words at blanks, tabs and newlines, and null
       words  are  discarded.   The  output is variable and command substituted and put in
       place of the original string.

       Command substitutions inside double quotes ('"') retain blanks and tabs; only  new-
       lines  force  new words.  The single final newline does not force a new word in any
       case.  It is thus possible for a command substitution to yield only part of a word,
       even if the command outputs a complete line.

       By  default,  the shell since version 6.12 replaces all newline and carriage return
       characters in the command by spaces.  If this is switched off by unsetting  csubst-
       nonl, newlines separate commands as usual.

   Filename substitution
       If  a  word  contains any of the characters '*', '?', '[' or '{' or begins with the
       character '~' it is a candidate for filename substitution, also  known  as  ''glob-
       bing''.   This  word is then regarded as a pattern (''glob-pattern''), and replaced
       with an alphabetically sorted list of file names which match the pattern.

       In matching filenames, the character '.' at the beginning of a filename or  immedi-
       ately  following  a  '/',  as well as the character '/' must be matched explicitly.
       The character '*' matches any string of characters, including the null string.  The
       character  '?'  matches any single character.  The sequence '[...]' matches any one
       of the characters enclosed.  Within '[...]', a pair of characters separated by  '-'
       matches any character lexically between the two.

       (+)  Some  glob-patterns  can  be negated: The sequence '[^...]' matches any single
       character not specified by the  characters  and/or  ranges  of  characters  in  the

       An entire glob-pattern can also be negated with '^':

           > echo *
           bang crash crunch ouch
           > echo ^cr*
           bang ouch

       Glob-patterns  which  do not use '?', '*', or '[]' or which use '{}' or '~' (below)
       are not negated correctly.

       The metanotation 'a{b,c,d}e' is a shorthand for 'abe ace ade'.  Left-to-right order
       is  preserved:  '/usr/source/s1/{oldls,ls}.c'  expands  to  '/usr/source/s1/oldls.c
       /usr/source/s1/ls.c'.  The results of matches are sorted separately at a low  level
       to  preserve this order: '../{memo,*box}' might expand to '../memo ../box ../mbox'.
       (Note that 'memo' was not sorted with the results of matching '*box'.)  It  is  not
       an  error when this construct expands to files which do not exist, but it is possi-
       ble to get an error from a command to which the expanded list is passed.  This con-
       struct  may  be  nested.   As a special case the words '{', '}' and '{}' are passed

       The character '~' at the beginning  of  a  filename  refers  to  home  directories.
       Standing  alone, i.e., '~', it expands to the invoker's home directory as reflected
       in the value of the home shell variable.  When followed by  a  name  consisting  of
       letters, digits and '-' characters the shell searches for a user with that name and
       substitutes their home directory;  thus  '~ken'  might  expand  to  '/usr/ken'  and
       '~ken/chmach'  to '/usr/ken/chmach'.  If the character '~' is followed by a charac-
       ter other than a letter or '/' or appears elsewhere than  at  the  beginning  of  a
       word,    it    is    left    undisturbed.    A   command   like   'setenv   MANPATH
       /usr/man:/usr/local/man:~/lib/man' does not, therefore, do home directory substitu-
       tion as one might hope.

       It  is an error for a glob-pattern containing '*', '?', '[' or '~', with or without
       '^', not to match any files.  However, only one pattern in a list of  glob-patterns
       must match a file (so that, e.g., 'rm *.a *.c *.o' would fail only if there were no
       files in the current directory ending in '.a', '.c', or '.o'), and if the nonomatch
       shell variable is set a pattern (or list of patterns) which matches nothing is left
       unchanged rather than causing an error.

       The noglob shell variable can be set to  prevent  filename  substitution,  and  the
       expand-glob  editor command, normally bound to '^X-*', can be used to interactively
       expand individual filename substitutions.

   Directory stack substitution (+)
       The directory stack is a list of directories,  numbered  from  zero,  used  by  the
       pushd,  popd  and  dirs  builtin commands (q.v.).  dirs can print, store in a file,
       restore and clear the directory stack at any time, and the  savedirs  and  dirsfile
       shell variables can be set to store the directory stack automatically on logout and
       restore it on login.  The dirstack shell variable can be examined to see the direc-
       tory stack and set to put arbitrary directories into the directory stack.

       The  character '=' followed by one or more digits expands to an entry in the direc-
       tory stack.  The special case '=-' expands to the last directory in the stack.  For

           > dirs -v
           0       /usr/bin
           1       /usr/spool/uucp
           2       /usr/accts/sys
           > echo =1
           > echo =0/calendar
           > echo =-

       The  noglob  and nonomatch shell variables and the expand-glob editor command apply
       to directory stack as well as filename substitutions.

   Other substitutions (+)
       There are several more transformations involving filenames, not strictly related to
       the  above  but mentioned here for completeness.  Any filename may be expanded to a
       full path when the symlinks variable (q.v.) is set to 'expand'.   Quoting  prevents
       this  expansion, and the normalize-path editor command does it on demand.  The nor-
       malize-command editor command expands commands in PATH into full paths  on  demand.
       Finally, cd and pushd interpret '-' as the old working directory (equivalent to the
       shell variable owd).  This is not a substitution at all, but an abbreviation recog-
       nized by only those commands.  Nonetheless, it too can be prevented by quoting.

       The  next  three  sections  describe how the shell executes commands and deals with
       their input and output.

   Simple commands, pipelines and sequences
       A simple command is a sequence of words, the first of which specifies  the  command
       to  be  executed.   A  series  of  simple commands joined by '|' characters forms a
       pipeline.  The output of each command in a pipeline is connected to  the  input  of
       the next.

       Simple  commands  and  pipelines may be joined into sequences with ';', and will be
       executed sequentially.  Commands and pipelines can also be  joined  into  sequences
       with  '||' or '&&', indicating, as in the C language, that the second is to be exe-
       cuted only if the first fails or succeeds respectively.

       A simple command, pipeline or sequence may be placed in parentheses, '()', to  form
       a  simple  command,  which may in turn be a component of a pipeline or sequence.  A
       command, pipeline or sequence can be executed without waiting for it  to  terminate
       by following it with an '&'.

   Builtin and non-builtin command execution
       Builtin  commands  are  executed  within the shell.  If any component of a pipeline
       except the last is a builtin command, the pipeline is executed in a subshell.

       Parenthesized commands are always executed in a subshell.

           (cd; pwd); pwd

       thus prints the home directory, leaving you where you were (printing this after the
       home directory), while

           cd; pwd

       leaves  you  in  the home directory.  Parenthesized commands are most often used to
       prevent cd from affecting the current shell.

       When a command to be executed is found not  to  be  a  builtin  command  the  shell
       attempts  to  execute  the  command  via execve(2).  Each word in the variable path
       names a directory in which the shell will look for the command.  If  the  shell  is
       not  given  a  -f  option,  the shell hashes the names in these directories into an
       internal table so that it will try an execve(2) in only a directory where there  is
       a possibility that the command resides there.  This greatly speeds command location
       when a large number of directories are present in the  search  path.  This  hashing
       mechanism is not used:

       1.  If hashing is turned explicitly off via unhash.

       2.  If the shell was given a -f argument.

       3.  For each directory component of path which does not begin with a '/'.

       4.  If the command contains a '/'.

       In  the  above  four cases the shell concatenates each component of the path vector
       with the given command name to form a path name of a file which it then attempts to
       execute it. If execution is successful, the search stops.

       If  the  file has execute permissions but is not an executable to the system (i.e.,
       it is neither an executable binary nor a script that  specifies  its  interpreter),
       then  it  is  assumed  to  be  a  file containing shell commands and a new shell is
       spawned to read it.  The shell special alias may be set to specify  an  interpreter
       other than the shell itself.

       On systems which do not understand the '#!' script interpreter convention the shell
       may be compiled to emulate it; see the version shell variable.  If  so,  the  shell
       checks  the  first  line of the file to see if it is of the form '#!interpreter arg
       ...'.  If it is, the shell starts interpreter with the given  args  and  feeds  the
       file to it on standard input.

       The standard input and standard output of a command may be redirected with the fol-
       lowing syntax:

       < name  Open file name (which is first variable, command and filename expanded)  as
               the standard input.
       << word Read  the shell input up to a line which is identical to word.  word is not
               subjected to variable, filename or command  substitution,  and  each  input
               line  is  compared  to word before any substitutions are done on this input
               line.  Unless a quoting '\', '"', '' or ''' appears in  word  variable  and
               command substitution is performed on the intervening lines, allowing '\' to
               quote '$', '\' and '''.  Commands which are substituted  have  all  blanks,
               tabs,  and  newlines  preserved,  except  for  the  final  newline which is
               dropped.  The resultant text is placed in an anonymous temporary file which
               is given to the command as standard input.
       > name
       >! name
       >& name
       >&! name
               The  file name is used as standard output.  If the file does not exist then
               it is created; if the file exists, it is truncated, its  previous  contents
               being lost.

               If  the shell variable noclobber is set, then the file must not exist or be
               a character special file (e.g., a terminal  or  '/dev/null')  or  an  error
               results.  This helps prevent accidental destruction of files.  In this case
               the '!' forms can be used to suppress this check.

               The forms involving '&' route the diagnostic output into the specified file
               as  well  as  the standard output.  name is expanded in the same way as '<'
               input filenames are.
       >> name
       >>& name
       >>! name
       >>&! name
               Like '>', but appends output to the end of name.   If  the  shell  variable
               noclobber is set, then it is an error for the file not to exist, unless one
               of the '!' forms is given.

       A command receives the environment in which the shell was invoked  as  modified  by
       the  input-output  parameters and the presence of the command in a pipeline.  Thus,
       unlike some previous shells, commands run from a file of  shell  commands  have  no
       access  to  the  text  of the commands by default; rather they receive the original
       standard input of the shell.  The '<<' mechanism should be used to  present  inline
       data.   This  permits  shell command scripts to function as components of pipelines
       and allows the shell to block read its input.  Note that the default standard input
       for  a command run detached is not the empty file /dev/null, but the original stan-
       dard input of the shell.  If this is a terminal and if the process attempts to read
       from  the  terminal, then the process will block and the user will be notified (see

       Diagnostic output may be directed through a pipe with the standard output.   Simply
       use the form '|&' rather than just '|'.

       The  shell  cannot  presently  redirect  diagnostic output without also redirecting
       standard output, but '(command > output-file) >& error-file' is often an acceptable
       workaround.   Either  output-file or error-file may be '/dev/tty' to send output to
       the terminal.

       Having described how the shell accepts, parses and executes command lines,  we  now
       turn to a variety of its useful features.

   Control flow
       The  shell  contains a number of commands which can be used to regulate the flow of
       control in command files (shell scripts) and (in limited but useful ways) from ter-
       minal  input.  These commands all operate by forcing the shell to reread or skip in
       its input and, due to the implementation, restrict the placement  of  some  of  the

       The  foreach, switch, and while statements, as well as the if-then-else form of the
       if statement, require that the major keywords appear in a single simple command  on
       an input line as shown below.

       If the shell's input is not seekable, the shell buffers up input whenever a loop is
       being read and performs seeks in this internal buffer to accomplish  the  rereading
       implied  by the loop.  (To the extent that this allows, backward gotos will succeed
       on non-seekable inputs.)

       The if, while and exit builtin commands use expressions with a common syntax.   The
       expressions  can include any of the operators described in the next three sections.
       Note that the @ builtin command (q.v.) has its own separate syntax.

   Logical, arithmetical and comparison operators
       These operators are similar to those of C  and  have  the  same  precedence.   They

           ||  &&  |  ^  &  ==  !=  =~  !~  <=  >=
           <  > <<  >>  +  -  *  /  %  !  ~  (  )

       Here  the precedence increases to the right, '==' '!=' '=~' and '!~', '<=' '>=' '<'
       and '>', '<<' and '>>', '+' and '-', '*' '/' and '%' being, in groups, at the  same
       level.   When multiple operators which have same precedence are used in one expres-
       sion, calculation must be done from operator of right side.  The '==' '!=' '=~' and
       '!~'  operators  compare their arguments as strings; all others operate on numbers.
       The operators '=~' and '!~' are like '!=' and '==' except that the right hand  side
       is  a  glob-pattern (see Filename substitution) against which the left hand operand
       is matched.  This reduces the need for use of the switch builtin command  in  shell
       scripts when all that is really needed is pattern matching.

       Null  or  missing arguments are considered '0'.  The results of all expressions are
       strings, which represent decimal numbers.  It is important to note that no two com-
       ponents  of an expression can appear in the same word; except when adjacent to com-
       ponents of expressions which are syntactically significant to the parser  ('&'  '|'
       '<' '>' '(' ')') they should be surrounded by spaces.

   Command exit status
       Commands can be executed in expressions and their exit status returned by enclosing
       them in braces ('{}').  Remember that the braces should be separated from the words
       of  the  command by spaces.  Command executions succeed, returning true, i.e., '1',
       if the command exits with status 0, otherwise they  fail,  returning  false,  i.e.,
       '0'.   If  more  detailed status information is required then the command should be
       executed outside of an expression and the status shell variable examined.

   File inquiry operators
       Some of these operators perform true/false tests  on  files  and  related  objects.
       They are of the form -op file, where op is one of

           r   Read access
           w   Write access
           x   Execute access
           X   Executable  in  the  path or shell builtin, e.g., '-X ls' and '-X ls-F' are
               generally true, but '-X /bin/ls' is not (+)
           e   Existence
           o   Ownership
           z   Zero size
           s   Non-zero size (+)
           f   Plain file
           d   Directory
           l   Symbolic link (+) *
           b   Block special file (+)
           c   Character special file (+)
           p   Named pipe (fifo) (+) *
           S   Socket special file (+) *
           u   Set-user-ID bit is set (+)
           g   Set-group-ID bit is set (+)
           k   Sticky bit is set (+)
           t   file (which must be a digit) is an open  file  descriptor  for  a  terminal
               device (+)
           R   Has been migrated (convex only) (+)
           L   Applies subsequent operators in a multiple-operator test to a symbolic link
               rather than to the file to which the link points (+) *

       file is command and filename expanded and then tested to see if it has  the  speci-
       fied  relationship to the real user.  If file does not exist or is inaccessible or,
       for the operators indicated by '*', if the specified file type does  not  exist  on
       the current system, then all enquiries return false, i.e., '0'.

       These  operators  may  be combined for conciseness: '-xy file' is equivalent to '-x
       file && -y file'.  (+) For example, '-fx' is true  (returns  '1')  for  plain  exe-
       cutable files, but not for directories.

       L  may  be used in a multiple-operator test to apply subsequent operators to a sym-
       bolic link rather than to the file to which the link points.  For  example,  '-lLo'
       is  true  for  links owned by the invoking user.  Lr, Lw and Lx are always true for
       links and false for non-links.  L has a different meaning when it is the last oper-
       ator in a multiple-operator test; see below.

       It is possible but not useful, and sometimes misleading, to combine operators which
       expect file to be a file with operators which do not, (e.g., X and t).  Following L
       with a non-file operator can lead to particularly strange results.

       Other operators return other information, i.e., not just '0' or '1'.  (+) They have
       the same format as before; op may be one of

           A       Last file access time, as the number of seconds since the epoch
           A:      Like A, but in timestamp format, e.g., 'Fri May 14 16:36:10 1993'
           M       Last file modification time
           M:      Like M, but in timestamp format
           C       Last inode modification time
           C:      Like C, but in timestamp format
           D       Device number
           I       Inode number
           F       Composite file identifier, in the form device:inode
           L       The name of the file pointed to by a symbolic link
           N       Number of (hard) links
           P       Permissions, in octal, without leading zero
           P:      Like P, with leading zero
           Pmode   Equivalent to '-P file & mode', e.g., '-P22 file' returns '22' if  file
                   is  writable  by  group and other, '20' if by group only, and '0' if by
           Pmode:  Like Pmode, with leading zero
           U       Numeric userid
           U:      Username, or the numeric userid if the username is unknown
           G       Numeric groupid
           G:      Groupname, or the numeric groupid if the groupname is unknown
           Z       Size, in bytes

       Only one of these operators may appear in a multiple-operator test, and it must  be
       the  last.   Note  that  L has a different meaning at the end of and elsewhere in a
       multiple-operator test.  Because '0' is a valid return  value  for  many  of  these
       operators,  they  do not return '0' when they fail: most return '-1', and F returns

       If the shell is compiled with POSIX defined (see the version shell  variable),  the
       result of a file inquiry is based on the permission bits of the file and not on the
       result of the access(2) system call.  For example, if one  tests  a  file  with  -w
       whose  permissions  would  ordinarily  allow  writing but which is on a file system
       mounted read-only, the test will succeed in a POSIX shell but fail in  a  non-POSIX

       File  inquiry  operators  can  also  be evaluated with the filetest builtin command
       (q.v.) (+).

       The shell associates a job with each pipeline.  It keeps a table of  current  jobs,
       printed by the jobs command, and assigns them small integer numbers.  When a job is
       started asynchronously with '&', the shell prints a line which looks like

           [1] 1234

       indicating that the job which was started asynchronously was job number 1  and  had
       one (top-level) process, whose process id was 1234.

       If  you are running a job and wish to do something else you may hit the suspend key
       (usually '^Z'), which sends a STOP signal to the current job.  The shell will  then
       normally  indicate  that the job has been 'Suspended' and print another prompt.  If
       the listjobs shell variable is set, all jobs will be listed like the  jobs  builtin
       command; if it is set to 'long' the listing will be in long format, like 'jobs -l'.
       You can then manipulate the state of the suspended job.  You  can  put  it  in  the
       ''background''  with the bg command or run some other commands and eventually bring
       the job back into the ''foreground'' with fg.  (See also the  run-fg-editor  editor
       command.)  A '^Z' takes effect immediately and is like an interrupt in that pending
       output and unread input are discarded when it is typed.  The wait  builtin  command
       causes the shell to wait for all background jobs to complete.

       The  '^]' key sends a delayed suspend signal, which does not generate a STOP signal
       until a program attempts to read(2) it, to the current job.  This can  usefully  be
       typed  ahead  when you have prepared some commands for a job which you wish to stop
       after it has read them.  The '^Y' key performs this function in  csh(1);  in  tcsh,
       '^Y' is an editing command.  (+)

       A  job  being  run  in  the background stops if it tries to read from the terminal.
       Background jobs are normally allowed to produce output, but this can be disabled by
       giving the command 'stty tostop'.  If you set this tty option, then background jobs
       will stop when they try to produce output like they do when they try to read input.

       There are several ways to refer to jobs in the shell.  The character '%' introduces
       a job name.  If you wish to refer to job number 1, you can name it as  '%1'.   Just
       naming  a  job  brings  it  to  the foreground; thus '%1' is a synonym for 'fg %1',
       bringing job 1 back into the foreground.  Similarly, saying '%1 &' resumes job 1 in
       the  background, just like 'bg %1'.  A job can also be named by an unambiguous pre-
       fix of the string typed in to start it: '%ex' would normally  restart  a  suspended
       ex(1)  job,  if  there were only one suspended job whose name began with the string
       'ex'.  It is also possible to say '%?string' to specify a job whose  text  contains
       string, if there is only one such job.

       The  shell maintains a notion of the current and previous jobs.  In output pertain-
       ing to jobs, the current job is marked with a '+' and the previous job with a  '-'.
       The  abbreviations '%+', '%', and (by analogy with the syntax of the history mecha-
       nism) '%%' all refer to the current job, and '%-' refers to the previous job.

       The job control mechanism requires that the stty(1) option 'new'  be  set  on  some
       systems.   It  is  an  artifact from a 'new' implementation of the tty driver which
       allows generation of interrupt characters from the keyboard to tell jobs  to  stop.
       See stty(1) and the setty builtin command for details on setting options in the new
       tty driver.

   Status reporting
       The shell learns immediately whenever a process changes state.  It normally informs
       you  whenever  a  job  becomes blocked so that no further progress is possible, but
       only right before it prints a prompt.  This is done so that it does  not  otherwise
       disturb  your work.  If, however, you set the shell variable notify, the shell will
       notify you immediately of changes of status in background jobs.  There  is  also  a
       shell  command  notify which marks a single process so that its status changes will
       be immediately reported.  By default notify marks the current process;  simply  say
       'notify' after starting a background job to mark it.

       When  you  try  to  leave the shell while jobs are stopped, you will be warned that
       'There are suspended jobs.' You may use the jobs command to see what they are.   If
       you  do this or immediately try to exit again, the shell will not warn you a second
       time, and the suspended jobs will be terminated.

   Automatic, periodic and timed events (+)
       There are various ways to run commands and take other actions automatically at var-
       ious  times  in  the  ''life  cycle''  of the shell.  They are summarized here, and
       described in detail under the appropriate Builtin commands, Special shell variables
       and Special aliases.

       The  sched  builtin command puts commands in a scheduled-event list, to be executed
       by the shell at a given time.

       The beepcmd, cwdcmd, periodic, precmd, postcmd, and jobcmd Special aliases  can  be
       set,  respectively, to execute commands when the shell wants to ring the bell, when
       the working directory changes, every tperiod minutes, before  each  prompt,  before
       each  command  gets  executed,  after each command gets executed, and when a job is
       started or is brought into the foreground.

       The autologout shell variable can be set to log out or lock the shell after a given
       number of minutes of inactivity.

       The mail shell variable can be set to check for new mail periodically.

       The  printexitvalue  shell variable can be set to print the exit status of commands
       which exit with a status other than zero.

       The rmstar shell variable can be set to ask the user, when 'rm *' is typed, if that
       is really what was meant.

       The  time  shell  variable can be set to execute the time builtin command after the
       completion of any process that takes more than a given number of CPU seconds.

       The watch and who shell variables can be set to report when selected users  log  in
       or out, and the log builtin command reports on those users at any time.

   Native Language System support (+)
       The  shell  is eight bit clean (if so compiled; see the version shell variable) and
       thus supports character sets needing this capability.  NLS support differs  depend-
       ing  on  whether  or not the shell was compiled to use the system's NLS (again, see
       version).  In either case, 7-bit ASCII is the default  character  code  (e.g.,  the
       classification  of  which  characters  are printable) and sorting, and changing the
       LANG or LC_CTYPE environment variables causes a check for possible changes in these

       When  using  the  system's  NLS,  the  setlocale(3) function is called to determine
       appropriate character code/classification and sorting (e.g., a 'en_CA.UTF-8'  would
       yield  "UTF-8" as a character code).  This function typically examines the LANG and
       LC_CTYPE environment variables; refer  to  the  system  documentation  for  further
       details.   When not using the system's NLS, the shell simulates it by assuming that
       the ISO 8859-1 character set is used whenever either of the LANG and LC_CTYPE vari-
       ables  are  set, regardless of their values.  Sorting is not affected for the simu-
       lated NLS.

       In addition, with both real and simulated NLS,  all  printable  characters  in  the
       range  \200-\377,  i.e., those that have M-char bindings, are automatically rebound
       to self-insert-command.  The corresponding binding for the escape-char sequence, if
       any,  is  left alone.  These characters are not rebound if the NOREBIND environment
       variable is set.  This may be useful for the simulated NLS or a primitive real  NLS
       which  assumes  full  ISO  8859-1.   Otherwise,  all  M-char  bindings in the range
       \240-\377 are effectively undone.  Explicitly  rebinding  the  relevant  keys  with
       bindkey is of course still possible.

       Unknown  characters (i.e., those that are neither printable nor control characters)
       are printed in the format \nnn.  If the tty is not in 8 bit mode, other 8 bit char-
       acters  are printed by converting them to ASCII and using standout mode.  The shell
       never changes the 7/8 bit mode of the tty and tracks user-initiated changes of  7/8
       bit  mode.   NLS  users (or, for that matter, those who want to use a meta key) may
       need to explicitly set the tty in 8 bit mode through the appropriate  stty(1)  com-
       mand in, e.g., the ~/.login file.

   OS variant support (+)
       A  number  of  new  builtin commands are provided to support features in particular
       operating systems.  All are described in detail in the Builtin commands section.

       On systems that support TCF (aix-ibm370, aix-ps2), getspath and  setspath  get  and
       set  the  system execution path, getxvers and setxvers get and set the experimental
       version prefix and migrate migrates processes  between  sites.   The  jobs  builtin
       prints the site on which each job is executing.

       Under  BS2000, bs2cmd executes commands of the underlying BS2000/OSD operating sys-

       Under Domain/OS, inlib adds shared libraries to the current  environment,  rootnode
       changes the rootnode and ver changes the systype.

       Under Mach, setpath is equivalent to Mach's setpath(1).

       Under Masscomp/RTU and Harris CX/UX, universe sets the universe.

       Under Harris CX/UX, ucb or att runs a command under the specified universe.

       Under Convex/OS, warp prints or sets the universe.

       The  VENDOR,  OSTYPE  and  MACHTYPE environment variables indicate respectively the
       vendor, operating system and machine type (microprocessor class or  machine  model)
       of the system on which the shell thinks it is running.  These are particularly use-
       ful when sharing one's home directory between several types of machines;  one  can,
       for example,

           set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)

       in  one's ~/.login and put executables compiled for each machine in the appropriate

       The version shell variable indicates what options were chosen when  the  shell  was

       Note  also  the  newgrp builtin, the afsuser and echo_style shell variables and the
       system-dependent locations of the shell's input files (see FILES).

   Signal handling
       Login shells ignore interrupts when reading the file ~/.logout.  The shell  ignores
       quit  signals unless started with -q.  Login shells catch the terminate signal, but
       non-login shells inherit the terminate behavior from their parents.  Other  signals
       have the values which the shell inherited from its parent.

       In  shell  scripts,  the shell's handling of interrupt and terminate signals can be
       controlled with onintr, and its handling of hangups can be controlled with hup  and

       The  shell exits on a hangup (see also the logout shell variable).  By default, the
       shell's children do too, but the shell does not send them a hangup when  it  exits.
       hup  arranges  for  the  shell to send a hangup to a child when it exits, and nohup
       sets a child to ignore hangups.

   Terminal management (+)
       The shell uses three different sets of terminal (''tty'') modes: 'edit', used  when
       editing,  'quote',  used  when quoting literal characters, and 'execute', used when
       executing commands.  The shell holds some settings in each mode constant,  so  com-
       mands which leave the tty in a confused state do not interfere with the shell.  The
       shell also matches changes in the speed and padding of the tty.  The  list  of  tty
       modes  that  are kept constant can be examined and modified with the setty builtin.
       Note that although the editor uses CBREAK mode (or its equivalent), it takes typed-
       ahead characters anyway.

       The  echotc, settc and telltc commands can be used to manipulate and debug terminal
       capabilities from the command line.

       On systems that support SIGWINCH or SIGWINDOW, the shell adapts to window  resizing
       automatically  and  adjusts the environment variables LINES and COLUMNS if set.  If
       the environment variable TERMCAP contains li# and co#  fields,  the  shell  adjusts
       them to reflect the new window size.

       The  next  sections  of this manual describe all of the available Builtin commands,
       Special aliases and Special shell variables.

   Builtin commands
       %job    A synonym for the fg builtin command.

       %job &  A synonym for the bg builtin command.

       :       Does nothing, successfully.

       @ name = expr
       @ name[index] = expr
       @ name++|--
       @ name[index]++|--
               The first form prints the values of all shell variables.

               The second form assigns the value of expr to name.  The third form  assigns
               the  value  of  expr  to  the index'th component of name; both name and its
               index'th component must already exist.

               expr may contain the operators '*', '+', etc., as in C.  If  expr  contains
               '<',  '>',  '&' or '' then at least that part of expr must be placed within
               '()'.  Note that the syntax of expr has nothing to do with  that  described
               under Expressions.

               The fourth and fifth forms increment ('++') or decrement ('--') name or its
               index'th component.

               The space between '@' and name is required.  The spaces  between  name  and
               '=' and between '=' and expr are optional.  Components of expr must be sep-
               arated by spaces.

       alias [name [wordlist]]
               Without arguments, prints all aliases.  With name,  prints  the  alias  for
               name.   With  name  and  wordlist,  assigns  wordlist as the alias of name.
               wordlist is command and filename substituted.  name may not be  'alias'  or
               'unalias'.  See also the unalias builtin command.

       alloc   Shows the amount of dynamic memory acquired, broken down into used and free
               memory.  With an argument shows the number of free and used blocks in  each
               size  category.   The  categories  start at size 8 and double at each step.
               This command's output may vary across system types, because  systems  other
               than the VAX may use a different memory allocator.

       bg [%job ...]
               Puts  the  specified jobs (or, without arguments, the current job) into the
               background, continuing each if it is stopped.   job  may  be  a  number,  a
               string, '', '%', '+' or '-' as described under Jobs.

       bindkey [-l|-d|-e|-v|-u] (+)
       bindkey [-a] [-b] [-k] [-r] [--] key (+)
       bindkey [-a] [-b] [-k] [-c|-s] [--] key command (+)
               Without options, the first form lists all bound keys and the editor command
               to which each is bound, the second form lists the editor command  to  which
               key  is  bound  and the third form binds the editor command command to key.
               Options include:

               -l  Lists all editor commands and a short description of each.
               -d  Binds all keys to the standard bindings for the default editor.
               -e  Binds all keys to the standard GNU Emacs-like bindings.
               -v  Binds all keys to the standard vi(1)-like bindings.
               -a  Lists or changes key-bindings in the alternative key map.  This is  the
                   key map used in vi command mode.
               -b  key  is  interpreted  as  a control character written ^character (e.g.,
                   '^A') or C-character (e.g., 'C-A'), a meta character written  M-charac-
                   ter  (e.g., 'M-A'), a function key written F-string (e.g., 'F-string'),
                   or an extended prefix key written X-character (e.g., 'X-A').
               -k  key is interpreted as a symbolic arrow key name, which may  be  one  of
                   'down', 'up', 'left' or 'right'.
               -r  Removes  key's  binding.  Be careful: 'bindkey -r' does not bind key to
                   self-insert-command (q.v.), it unbinds key completely.
               -c  command is interpreted as a builtin or external command instead  of  an
                   editor command.
               -s  command is taken as a literal string and treated as terminal input when
                   key is typed.  Bound keys in command are themselves reinterpreted,  and
                   this continues for ten levels of interpretation.
               --  Forces a break from option processing, so the next word is taken as key
                   even if it begins with '-'.
               -u (or any invalid option)
                   Prints a usage message.

               key may be a single character or a string.  If a  command  is  bound  to  a
               string,  the first character of the string is bound to sequence-lead-in and
               the entire string is bound to the command.

               Control characters in key can be literal (they can be  typed  by  preceding
               them  with  the  editor  command  quoted-insert, normally bound to '^V') or
               written caret-character style, e.g., '^A'.  Delete is written '^?'  (caret-
               question  mark).   key and command can contain backslashed escape sequences
               (in the style of System V echo(1)) as follows:

                   \a      Bell
                   \b      Backspace
                   \e      Escape
                   \f      Form feed
                   \n      Newline
                   \r      Carriage return
                   \t      Horizontal tab
                   \v      Vertical tab
                   \nnn    The ASCII character corresponding to the octal number nnn

               '\' nullifies the special meaning of the following  character,  if  it  has
               any, notably '\' and '^'.

       bs2cmd bs2000-command (+)
               Passes bs2000-command to the BS2000 command interpreter for execution. Only
               non-interactive commands can be executed, and it is not possible to execute
               any command that would overlay the image of the current process, like /EXE-
               CUTE or /CALL-PROCEDURE. (BS2000 only)

       break   Causes execution to resume after the end of the nearest  enclosing  foreach
               or while.  The remaining commands on the current line are executed.  Multi-
               level breaks are thus possible by writing them all on one line.

       breaksw Causes a break from a switch, resuming after the endsw.

       builtins (+)
               Prints the names of all builtin commands.

       bye (+) A synonym for the logout builtin command.  Available only if the shell  was
               so compiled; see the version shell variable.

       case label:
               A label in a switch statement as discussed below.

       cd [-p] [-l] [-n|-v] [name]
               If  a  directory  name  is  given, changes the shell's working directory to
               name.  If not, changes to home.  If name is '-' it is  interpreted  as  the
               previous working directory (see Other substitutions).  (+) If name is not a
               subdirectory of the current directory (and does not begin with '/', './' or
               '../'), each component of the variable cdpath is checked to see if it has a
               subdirectory name.  Finally, if all else fails but name is a shell variable
               whose  value  begins  with '/', then this is tried to see if it is a direc-

               With -p, prints the final directory stack, just like dirs.  The -l, -n  and
               -v flags have the same effect on cd as on dirs, and they imply -p.  (+)

               See also the implicitcd shell variable.

       chdir   A synonym for the cd builtin command.

       complete [command [word/pattern/list[:select]/[[suffix]/] ...]] (+)
               Without  arguments, lists all completions.  With command, lists completions
               for command.  With command and word etc., defines completions.

               command may be a full command name or a glob-pattern (see Filename  substi-
               tution).   It can begin with '-' to indicate that completion should be used
               only when command is ambiguous.

               word specifies which word relative to the current word is to be  completed,
               and may be one of the following:

                   c   Current-word  completion.   pattern  is  a  glob-pattern which must
                       match the beginning of the current word on the command line.   pat-
                       tern is ignored when completing the current word.
                   C   Like c, but includes pattern when completing the current word.
                   n   Next-word  completion.   pattern is a glob-pattern which must match
                       the beginning of the previous word on the command line.
                   N   Like n, but must match the beginning of the  word  two  before  the
                       current word.
                   p   Position-dependent  completion.   pattern  is a numeric range, with
                       the same syntax used to index shell variables, which  must  include
                       the current word.

               list, the list of possible completions, may be one of the following:

                   a       Aliases
                   b       Bindings (editor commands)
                   c       Commands (builtin or external commands)
                   C       External commands which begin with the supplied path prefix
                   d       Directories
                   D       Directories which begin with the supplied path prefix
                   e       Environment variables
                   f       Filenames
                   F       Filenames which begin with the supplied path prefix
                   g       Groupnames
                   j       Jobs
                   l       Limits
                   n       Nothing
                   s       Shell variables
                   S       Signals
                   t       Plain (''text'') files
                   T       Plain  (''text'') files which begin with the supplied path pre-
                   v       Any variables
                   u       Usernames
                   x       Like n, but prints select when list-choices is used.
                   X       Completions
                   $var    Words from the variable var
                   (...)   Words from the given list
                   '...'   Words from the output of command

               select is an optional glob-pattern.  If given, words from  only  list  that
               match select are considered and the fignore shell variable is ignored.  The
               last three types of completion may not have a select pattern,  and  x  uses
               select  as  an  explanatory message when the list-choices editor command is

               suffix is a single character to be appended to a successful completion.  If
               null,  no  character  is  appended.   If  omitted (in which case the fourth
               delimiter can also be omitted), a slash is appended to  directories  and  a
               space to other words.

               command invoked from '...' version has additional environment variable set,
               the variable name is COMMAND_LINE and contains (as its name indicates) con-
               tents  of  the current (already typed in) command line. One can examine and
               use contents of the COMMAND_LINE variable in her  custom  script  to  build
               more  sophisticated completions (see completion for svn(1) included in this

               Now for some examples.  Some commands take only directories  as  arguments,
               so there's no point completing plain files.

                   > complete cd 'p/1/d/'

               completes  only the first word following 'cd' ('p/1') with a directory.  p-
               type completion can also be used to narrow down command completion:

                   > co[^D]
                   complete compress
                   > complete -co* 'p/0/(compress)/'
                   > co[^D]
                   > compress

               This completion completes commands (words in position 0, 'p/0') which begin
               with  'co' (thus matching 'co*') to 'compress' (the only word in the list).
               The leading '-' indicates that this completion is  to  be  used  with  only
               ambiguous commands.

                   > complete find 'n/-user/u/'

               is  an example of n-type completion.  Any word following 'find' and immedi-
               ately following '-user' is completed from the list of users.

                   > complete cc 'c/-I/d/'

               demonstrates c-type completion.  Any word following 'cc' and beginning with
               '-I'  is completed as a directory.  '-I' is not taken as part of the direc-
               tory because we used lowercase c.

               Different lists are useful with different commands.

                   > complete alias 'p/1/a/'
                   > complete man 'p/*/c/'
                   > complete set 'p/1/s/'
                   > complete true 'p/1/x:Truth has no options./'

               These complete words following 'alias' with aliases, 'man'  with  commands,
               and 'set' with shell variables.  'true' doesn't have any options, so x does
               nothing when completion is attempted and prints  'Truth  has  no  options.'
               when completion choices are listed.

               Note  that the man example, and several other examples below, could just as
               well have used 'c/*' or 'n/*' as 'p/*'.

               Words can be completed from a variable evaluated at completion time,

                   > complete ftp 'p/1/$hostnames/'
                   > set hostnames = (
                   > ftp [^D]
                   > ftp [^C]
                   > set hostnames = (
                   > ftp [^D]

               or from a command run at completion time:

                   > complete kill 'p/*/'ps | awk \{print\ \$1\}'/'
                   > kill -9 [^D]
                   23113 23377 23380 23406 23429 23529 23530 PID

               Note that the complete command does not itself quote its arguments, so  the
               braces, space and '$' in '{print $1}' must be quoted explicitly.

               One command can have multiple completions:

                   > complete dbx 'p/2/(core)/' 'p/*/c/'

               completes  the  second argument to 'dbx' with the word 'core' and all other
               arguments with commands.  Note that the positional completion is  specified
               before  the  next-word  completion.  Because completions are evaluated from
               left to right, if the next-word completion were specified  first  it  would
               always  match  and the positional completion would never be executed.  This
               is a common mistake when defining a completion.

               The select pattern is useful when a command takes files with only  particu-
               lar forms as arguments.  For example,

                   > complete cc 'p/*/f:*.[cao]/'

               completes  'cc'  arguments  to  files  ending  in only '.c', '.a', or '.o'.
               select can  also  exclude  files,  using  negation  of  a  glob-pattern  as
               described under Filename substitution.  One might use

                   > complete rm 'p/*/f:^*.{c,h,cc,C,tex,1,man,l,y}/'

               to exclude precious source code from 'rm' completion.  Of course, one could
               still type excluded names manually or  override  the  completion  mechanism
               using the complete-word-raw or list-choices-raw editor commands (q.v.).

               The  'C',  'D',  'F'  and  'T' lists are like 'c', 'd', 'f' and 't' respec-
               tively, but they use the select argument in a different  way:  to  restrict
               completion  to files beginning with a particular path prefix.  For example,
               the Elm mail program uses '=' as an abbreviation for one's mail  directory.
               One might use

                   > complete elm c@=@F:$HOME/Mail/@

               to  complete  'elm -f =' as if it were 'elm -f ~/Mail/'.  Note that we used
               '@' instead of '/' to avoid confusion with the select argument, and we used
               '$HOME'  instead  of  '~' because home directory substitution works at only
               the beginning of a word.

               suffix is used to add a nonstandard suffix (not space or '/'  for  directo-
               ries) to completed words.

                   > complete finger 'c/*@/$hostnames/' 'p/1/u/@'

               completes arguments to 'finger' from the list of users, appends an '@', and
               then completes after the '@' from the 'hostnames' variable.  Note again the
               order in which the completions are specified.

               Finally, here's a complex example for inspiration:

                   > complete find \
                   'n/-name/f/' 'n/-newer/f/' 'n/-{,n}cpio/f/' \
                   ?n/-exec/c/' 'n/-ok/c/' 'n/-user/u/' \
                   'n/-group/g/' 'n/-fstype/(nfs 4.2)/' \
                   'n/-type/(b c d f l p s)/' \
                   ?c/-/(name newer cpio ncpio exec ok user \
                   group fstype type atime ctime depth inum \
                   ls mtime nogroup nouser perm print prune \
                   size xdev)/' \

               This  completes words following '-name', '-newer', '-cpio' or 'ncpio' (note
               the pattern which matches both) to files, words following '-exec' or  '-ok'
               to commands, words following 'user' and 'group' to users and groups respec-
               tively and words following '-fstype' or '-type' to  members  of  the  given
               lists.  It also completes the switches themselves from the given list (note
               the use of c-type completion) and completes  anything  not  otherwise  com-
               pleted to a directory.  Whew.

               Remember  that  programmed  completions  are ignored if the word being com-
               pleted is a tilde substitution (beginning with '~') or a  variable  (begin-
               ning  with  '$').   complete is an experimental feature, and the syntax may
               change in future versions of the shell.  See also  the  uncomplete  builtin

               Continues execution of the nearest enclosing while or foreach.  The rest of
               the commands on the current line are executed.

               Labels the default case in a switch statement.  It should  come  after  all
               case labels.

       dirs [-l] [-n|-v]
       dirs -S|-L [filename] (+)
       dirs -c (+)
               The  first form prints the directory stack.  The top of the stack is at the
               left and the first directory in the stack is the current  directory.   With
               -l,  '~'  or  '~name'  in  the output is expanded explicitly to home or the
               pathname of the home directory for user name.  (+)  With  -n,  entries  are
               wrapped before they reach the edge of the screen.  (+) With -v, entries are
               printed one per line, preceded by their stack positions.  (+) If more  than
               one  of  -n  or  -v is given, -v takes precedence.  -p is accepted but does

               With -S, the second form saves the directory stack to filename as a  series
               of  cd  and  pushd commands.  With -L, the shell sources filename, which is
               presumably a directory stack file saved by the -S option  or  the  savedirs
               mechanism.   In  either case, dirsfile is used if filename is not given and
               ~/.cshdirs is used if dirsfile is unset.

               Note that login shells do the equivalent of 'dirs -L' on  startup  and,  if
               savedirs  is set, 'dirs -S' before exiting.  Because only ~/.tcshrc is nor-
               mally sourced before ~/.cshdirs, dirsfile should be set in ~/.tcshrc rather
               than ~/.login.

               The last form clears the directory stack.

       echo [-n] word ...
               Writes  each  word  to the shell's standard output, separated by spaces and
               terminated with a newline.  The echo_style shell variable  may  be  set  to
               emulate  (or not) the flags and escape sequences of the BSD and/or System V
               versions of echo; see echo(1).

       echotc [-sv] arg ... (+)
               Exercises the terminal capabilities (see termcap(5)) in args.  For example,
               'echotc home' sends the cursor to the home position, 'echotc cm 3 10' sends
               it to column 3 and row 10, and 'echotc ts 0; echo "This is a test."; echotc
               fs' prints "This is a test."  in the status line.

               If  arg  is  'baud', 'cols', 'lines', 'meta' or 'tabs', prints the value of
               that capability ("yes" or "no" indicating that the terminal  does  or  does
               not  have  that  capability).  One might use this to make the output from a
               shell script less verbose on slow terminals, or limit command output to the
               number of lines on the screen:

                   > set history='echotc lines'
                   > @ history--

               Termcap  strings  may contain wildcards which will not echo correctly.  One
               should use double quotes when setting a shell variable to a terminal  capa-
               bility string, as in the following example that places the date in the sta-
               tus line:

                   > set tosl="'echotc ts 0'"
                   > set frsl="'echotc fs'"
                   > echo -n "$tosl";date; echo -n "$frsl"

               With -s, nonexistent capabilities return the empty string rather than caus-
               ing an error.  With -v, messages are verbose.

       endsw   See the description of the foreach, if, switch, and while statements below.

       eval arg ...
               Treats the arguments as input to the shell and executes the resulting  com-
               mand(s)  in the context of the current shell.  This is usually used to exe-
               cute commands generated as the result of command or variable  substitution,
               because  parsing occurs before these substitutions.  See tset(1) for a sam-
               ple use of eval.

       exec command
               Executes the specified command in place of the current shell.

       exit [expr]
               The shell exits either with the value of the specified expr (an expression,
               as described under Expressions) or, without expr, with the value 0.

       fg [%job ...]
               Brings the specified jobs (or, without arguments, the current job) into the
               foreground, continuing each if it is stopped.   job  may  be  a  number,  a
               string,  '', '%', '+' or '-' as described under Jobs.  See also the run-fg-
               editor editor command.

       filetest -op file ... (+)
               Applies op (which is a  file  inquiry  operator  as  described  under  File
               inquiry  operators)  to  each file and returns the results as a space-sepa-
               rated list.

       foreach name (wordlist)
       end     Successively sets the variable name to each member of wordlist and executes
               the  sequence of commands between this command and the matching end.  (Both
               foreach and end must appear alone on separate lines.)  The builtin  command
               continue  may be used to continue the loop prematurely and the builtin com-
               mand break to terminate it prematurely.  When this command is read from the
               terminal,  the  loop  is  read once prompting with 'foreach? ' (or prompt2)
               before any statements in the loop are executed.  If you make a mistake typ-
               ing in a loop at the terminal you can rub it out.

       getspath (+)
               Prints the system execution path.  (TCF only)

       getxvers (+)
               Prints the experimental version prefix.  (TCF only)

       glob wordlist
               Like echo, but the '-n' parameter is not recognized and words are delimited
               by null characters in the output.  Useful for programs which  wish  to  use
               the shell to filename expand a list of words.

       goto word
               word  is  filename  and  command-substituted  to yield a string of the form
               'label'.  The shell rewinds its input as much as possible, searches  for  a
               line of the form 'label:', possibly preceded by blanks or tabs, and contin-
               ues execution after that line.

               Prints a statistics line indicating how effective the internal  hash  table
               has  been at locating commands (and avoiding exec's).  An exec is attempted
               for each component of the path where the hash function indicates a possible
               hit, and in each component which does not begin with a '/'.

               On machines without vfork(2), prints only the number and size of hash buck-

       history [-hTr] [n]
       history -S|-L|-M [filename] (+)
       history -c (+)
               The first form prints the history event list.  If n is  given  only  the  n
               most  recent  events  are  printed  or saved.  With -h, the history list is
               printed without leading  numbers.   If  -T  is  specified,  timestamps  are
               printed  also in comment form.  (This can be used to produce files suitable
               for loading with 'history -L' or 'source  -h'.)   With  -r,  the  order  of
               printing is most recent first rather than oldest first.

               With  -S, the second form saves the history list to filename.  If the first
               word of the savehist shell variable is set to a number, at most  that  many
               lines  are  saved.   If  the second word of savehist is set to 'merge', the
               history list is merged with the existing history file instead of  replacing
               it (if there is one) and sorted by time stamp.  (+) Merging is intended for
               an environment like the X Window System with several shells in simultaneous
               use.   Currently  it  succeeds  only  when the shells quit nicely one after

               With -L, the shell appends filename, which is  presumably  a  history  list
               saved  by the -S option or the savehist mechanism, to the history list.  -M
               is like -L, but the contents of filename are merged into the  history  list
               and  sorted  by timestamp.  In either case, histfile is used if filename is
               not given and ~/.history is used if histfile is  unset.   'history  -L'  is
               exactly like 'source -h' except that it does not require a filename.

               Note that login shells do the equivalent of 'history -L' on startup and, if
               savehist is set, 'history -S' before exiting.  Because  only  ~/.tcshrc  is
               normally  sourced  before  ~/.history,  histfile should be set in ~/.tcshrc
               rather than ~/.login.

               If histlit is set, the first and second forms print and  save  the  literal
               (unexpanded) form of the history list.

               The last form clears the history list.

       hup [command] (+)
               With  command,  runs  command such that it will exit on a hangup signal and
               arranges for the shell to send it a hangup signal  when  the  shell  exits.
               Note  that  commands may set their own response to hangups, overriding hup.
               Without an argument (allowed in only a shell script), causes the  shell  to
               exit on a hangup for the remainder of the script.  See also Signal handling
               and the nohup builtin command.

       if (expr) command
               If expr (an expression, as described  under  Expressions)  evaluates  true,
               then  command is executed.  Variable substitution on command happens early,
               at the same time it does for the rest of the if command.  command must be a
               simple command, not an alias, a pipeline, a command list or a parenthesized
               command list, but it may have arguments.  Input/output  redirection  occurs
               even if expr is false and command is thus not executed; this is a bug.

       if (expr) then
       else if (expr2) then
       endif   If  the specified expr is true then the commands to the first else are exe-
               cuted; otherwise if expr2 is true then the commands to the second else  are
               executed, etc.  Any number of else-if pairs are possible; only one endif is
               needed.  The else part is likewise optional.  (The  words  else  and  endif
               must  appear  at  the beginning of input lines; the if must appear alone on
               its input line or after an else.)

       inlib shared-library ... (+)
               Adds each shared-library to the current environment.  There is  no  way  to
               remove a shared library.  (Domain/OS only)

       jobs [-l]
               Lists  the active jobs.  With -l, lists process IDs in addition to the nor-
               mal information.  On TCF systems, prints the site on which each job is exe-

       kill [-s signal] %job|pid ...
       kill -l The  first  and  second  forms  sends  the specified signal (or, if none is
               given, the TERM (terminate) signal) to the  specified  jobs  or  processes.
               job may be a number, a string, '', '%', '+' or '-' as described under Jobs.
               Signals  are  either  given  by  number   or   by   name   (as   given   in
               /usr/include/signal.h,  stripped of the prefix 'SIG').  There is no default
               job; saying just 'kill' does not send a signal to the current job.  If  the
               signal being sent is TERM (terminate) or HUP (hangup), then the job or pro-
               cess is sent a CONT (continue) signal as well.  The third  form  lists  the
               signal names.

       limit [-h] [resource [maximum-use]]
               Limits  the  consumption by the current process and each process it creates
               to not individually exceed maximum-use on the specified  resource.   If  no
               maximum-use  is given, then the current limit is printed; if no resource is
               given, then all limitations are given.  If the -h flag is given,  the  hard
               limits  are  used  instead of the current limits.  The hard limits impose a
               ceiling on the values of the current limits.  Only the super-user may raise
               the  hard  limits,  but a user may lower or raise the current limits within
               the legal range.

               Controllable resources currently include (if supported by the OS):

                      the maximum number of cpu-seconds to be used by each process

                      the largest single file which can be created

                      the maximum growth of the data+stack region via sbrk(2)  beyond  the
                      end of the program text

                      the maximum size of the automatically-extended stack region

                      the size of the largest core dump that will be created

                      the  maximum  amount of physical memory a process may have allocated
                      to it at a given time (this is not implemented in  the  2.6  kernel.
                      The  value  is  meaningless  and  changing  this  value will have no

                      the maximum amount of memory a process may allocate per brk() system

               descriptors or openfiles
                      the maximum number of open files for this process

                      the maximum number of threads for this process

                      the maximum size which a process may lock into memory using mlock(2)

                      the maximum number of simultaneous processes for this user id

               sbsize the maximum size of socket buffer usage for this user

                      the maximum amount of swap space reserved or used for this user

               maximum-use may be given as a (floating point or integer)  number  followed
               by  a scale factor.  For all limits other than cputime the default scale is
               'k' or 'kilobytes' (1024 bytes); a scale factor of 'm' or  'megabytes'  may
               also  be used.  For cputime the default scaling is 'seconds', while 'm' for
               minutes or 'h' for hours, or a time of the form 'mm:ss' giving minutes  and
               seconds may be used.

               For  both  resource  names  and  scale factors, unambiguous prefixes of the
               names suffice.

       log (+) Prints the watch shell variable and reports on each user indicated in watch
               who  is  logged  in,  regardless  of  when  they  last logged in.  See also

       login   Terminates a login shell, replacing it with an instance of /bin/login. This
               is one way to log off, included for compatibility with sh(1).

       logout  Terminates a login shell.  Especially useful if ignoreeof is set.

       ls-F [-switch ...] [file ...] (+)
               Lists files like 'ls -F', but much faster.  It identifies each type of spe-
               cial file in the listing with a special character:

               /   Directory
               *   Executable
               #   Block device
               %   Character device
               |   Named pipe (systems with named pipes only)
               =   Socket (systems with sockets only)
               @   Symbolic link (systems with symbolic links only)
               +   Hidden directory (AIX only) or context dependent (HP/UX only)
               :   Network special (HP/UX only)

               If the listlinks shell variable is set, symbolic links  are  identified  in
               more detail (on only systems that have them, of course):

               @   Symbolic link to a non-directory
               >   Symbolic link to a directory
               &   Symbolic link to nowhere

               listlinks  also slows down ls-F and causes partitions holding files pointed
               to by symbolic links to be mounted.

               If the listflags shell variable is set to 'x', 'a' or 'A', or any  combina-
               tion  thereof  (e.g.,  'xA'), they are used as flags to ls-F, making it act
               like 'ls -xF', 'ls -Fa', 'ls -FA' or a combination (e.g., 'ls  -FxA').   On
               machines  where 'ls -C' is not the default, ls-F acts like 'ls -CF', unless
               listflags contains an 'x', in which case  it  acts  like  'ls  -xF'.   ls-F
               passes  its  arguments  to  ls(1) if it is given any switches, so 'alias ls
               ls-F' generally does the right thing.

               The ls-F builtin can list files using different  colors  depending  on  the
               filetype or extension.  See the color tcsh variable and the LS_COLORS envi-
               ronment variable.

       migrate [-site] pid|%jobid ... (+)
       migrate -site (+)
               The first form migrates the process or job to the  site  specified  or  the
               default  site determined by the system path.  The second form is equivalent
               to 'migrate -site $$': it migrates the current  process  to  the  specified
               site.   Migrating  the  shell itself can cause unexpected behavior, because
               the shell does not like to lose its tty.  (TCF only)

       newgrp [-] group (+)
               Equivalent to 'exec newgrp'; see newgrp(1).  Available only  if  the  shell
               was so compiled; see the version shell variable.

       nice [+number] [command]
               Sets  the  scheduling priority for the shell to number, or, without number,
               to 4.  With command, runs command at the appropriate priority.  The greater
               the number, the less cpu the process gets.  The super-user may specify neg-
               ative priority by using 'nice -number ...'.  Command is always executed  in
               a  sub-shell,  and  the restrictions placed on commands in simple if state-
               ments apply.

       nohup [command]
               With command, runs command such that it will ignore hangup  signals.   Note
               that  commands  may  set  their  own response to hangups, overriding nohup.
               Without an argument (allowed in only a shell script), causes the  shell  to
               ignore  hangups  for the remainder of the script.  See also Signal handling
               and the hup builtin command.

       notify [%job ...]
               Causes the shell to notify the user asynchronously when the status  of  any
               of  the specified jobs (or, without %job, the current job) changes, instead
               of waiting until the next prompt as is usual.   job  may  be  a  number,  a
               string,  '',  '%', '+' or '-' as described under Jobs.  See also the notify
               shell variable.

       onintr [-|label]
               Controls the  action  of  the  shell  on  interrupts.   Without  arguments,
               restores  the default action of the shell on interrupts, which is to termi-
               nate shell scripts or to return to the terminal command input level.   With
               '-',  causes all interrupts to be ignored.  With label, causes the shell to
               execute a 'goto label' when an interrupt is received  or  a  child  process
               terminates because it was interrupted.

               onintr  is  ignored  if the shell is running detached and in system startup
               files (see FILES), where interrupts are disabled anyway.

       popd [-p] [-l] [-n|-v] [+n]
               Without arguments, pops the directory stack and  returns  to  the  new  top
               directory.  With a number '+n', discards the n'th entry in the stack.

               Finally, all forms of popd print the final directory stack, just like dirs.
               The pushdsilent shell variable can be set to prevent this and the  -p  flag
               can  be  given  to  override pushdsilent.  The -l, -n and -v flags have the
               same effect on popd as on dirs.  (+)

       printenv [name] (+)
               Prints the names and values of all environment variables or, with name, the
               value of the environment variable name.

       pushd [-p] [-l] [-n|-v] [name|+n]
               Without  arguments,  exchanges the top two elements of the directory stack.
               If pushdtohome is set, pushd without arguments does  'pushd  ~',  like  cd.
               (+)  With  name,  pushes  the  current working directory onto the directory
               stack and changes to name.  If name is '-' it is interpreted as the  previ-
               ous  working directory (see Filename substitution).  (+) If dunique is set,
               pushd removes any instances of name from the stack before pushing  it  onto
               the  stack.   (+) With a number '+n', rotates the nth element of the direc-
               tory stack around to be the top element and changes to it.  If dextract  is
               set, however, 'pushd +n' extracts the nth directory, pushes it onto the top
               of the stack and changes to it.  (+)

               Finally, all forms of pushd print the  final  directory  stack,  just  like
               dirs.  The pushdsilent shell variable can be set to prevent this and the -p
               flag can be given to override pushdsilent.  The -l, -n and  -v  flags  have
               the same effect on pushd as on dirs.  (+)

       rehash  Causes  the  internal  hash table of the contents of the directories in the
               path variable to be recomputed.  This is needed if new commands  are  added
               to  directories  in path while you are logged in.  This should be necessary
               only if you add commands to one of your own directories, or  if  a  systems
               programmer  changes  the  contents  of one of the system directories.  Also
               flushes the cache of home directories built by tilde expansion.

       repeat count command
               The specified command, which is subject to the  same  restrictions  as  the
               command  in  the one line if statement above, is executed count times.  I/O
               redirections occur exactly once, even if count is 0.

       rootnode //nodename (+)
               Changes the rootnode to //nodename, so that  '/'  will  be  interpreted  as
               '//nodename'.  (Domain/OS only)

       sched (+)
       sched [+]hh:mm command (+)
       sched -n (+)
               The  first  form prints the scheduled-event list.  The sched shell variable
               may be set to define the  format  in  which  the  scheduled-event  list  is
               printed.   The  second  form adds command to the scheduled-event list.  For

                   > sched 11:00 echo It\'s eleven o\'clock.

               causes the shell to echo 'It's eleven o'clock.' at 11 AM.  The time may  be
               in 12-hour AM/PM format

                   > sched 5pm set prompt='[%h] It\'s after 5; go home: >'

               or may be relative to the current time:

                   > sched +2:15 /usr/lib/uucp/uucico -r1 -sother

               A  relative  time  specification  may not use AM/PM format.  The third form
               removes item n from the event list:

                   > sched
                        1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother
                        2  Wed Apr  4 17:00  set prompt=[%h] It's after 5; go home: >
                   > sched -2
                   > sched
                        1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother

               A command in the scheduled-event list is executed  just  before  the  first
               prompt is printed after the time when the command is scheduled.  It is pos-
               sible to miss the exact time when the command is to be run, but an  overdue
               command  will  execute at the next prompt.  A command which comes due while
               the shell is waiting for user input is executed immediately.  However, nor-
               mal operation of an already-running command will not be interrupted so that
               a scheduled-event list element may be run.

               This mechanism is similar to, but not the same as,  the  at(1)  command  on
               some Unix systems.  Its major disadvantage is that it may not run a command
               at exactly the specified time.  Its major advantage is that  because  sched
               runs  directly  from  the shell, it has access to shell variables and other
               structures.  This provides a mechanism for changing one's working  environ-
               ment based on the time of day.

       set name ...
       set name=word ...
       set [-r] [-f|-l] name=(wordlist) ... (+)
       set name[index]=word ...
       set -r (+)
       set -r name ... (+)
       set -r name=word ... (+)
               The  first  form  of  the  command prints the value of all shell variables.
               Variables which contain more than a single word print  as  a  parenthesized
               word  list.   The second form sets name to the null string.  The third form
               sets name to the single word.  The fourth form sets name  to  the  list  of
               words  in  wordlist.   In  all  cases  the  value  is  command and filename
               expanded.  If -r is specified, the value is set read-only.  If -f or -l are
               specified, set only unique words keeping their order.  -f prefers the first
               occurrence of a word, and -l the last.  The fifth form  sets  the  index'th
               component  of  name  to word; this component must already exist.  The sixth
               form lists only the names of all shell variables that are  read-only.   The
               seventh  form  makes  name  read-only,  whether or not it has a value.  The
               eighth form is the same as the third form, but make name read-only  at  the
               same time.

               These arguments can be repeated to set and/or make read-only multiple vari-
               ables in a single set command.  Note, however, that variable expansion hap-
               pens  for  all arguments before any setting occurs.  Note also that '=' can
               be adjacent to both name and word or separated from both by whitespace, but
               cannot  be  adjacent  to only one or the other.  See also the unset builtin

       setenv [name [value]]
               Without arguments, prints the names and values  of  all  environment  vari-
               ables.  Given name, sets the environment variable name to value or, without
               value, to the null string.

       setpath path (+)
               Equivalent to setpath(1).  (Mach only)

       setspath LOCAL|site|cpu ... (+)
               Sets the system execution path.  (TCF only)

       settc cap value (+)
               Tells the shell to believe that the terminal capability cap (as defined  in
               termcap(5)) has the value value.  No sanity checking is done.  Concept ter-
               minal users may have to 'settc xn no' to get proper wrapping at the  right-
               most column.

       setty [-d|-q|-x] [-a] [[+|-]mode] (+)
               Controls which tty modes (see Terminal management) the shell does not allow
               to change.  -d, -q or -x tells setty to act on the 'edit', 'quote' or 'exe-
               cute'  set  of  tty  modes respectively; without -d, -q or -x, 'execute' is

               Without other arguments, setty lists the modes in the chosen set which  are
               fixed  on  ('+mode')  or  off ('-mode').  The available modes, and thus the
               display, vary from system to system.  With -a, lists all tty modes  in  the
               chosen set whether or not they are fixed.  With +mode, -mode or mode, fixes
               mode on or off or removes control from mode in the chosen set.   For  exam-
               ple, 'setty +echok echoe' fixes 'echok' mode on and allows commands to turn
               'echoe' mode on or off, both when the shell is executing commands.

       setxvers [string] (+)
               Set the experimental version prefix to string, or removes it if  string  is
               omitted.  (TCF only)

       shift [variable]
               Without  arguments,  discards argv[1] and shifts the members of argv to the
               left.  It is an error for argv not to be set or to have less than one  word
               as value.  With variable, performs the same function on variable.

       source [-h] name [args ...]
               The  shell  reads  and  executes  commands from name.  The commands are not
               placed on the history list.  If any args are  given,  they  are  placed  in
               argv.  (+) source commands may be nested; if they are nested too deeply the
               shell may run out of file descriptors.  An error in a source at  any  level
               terminates all nested source commands.  With -h, commands are placed on the
               history list instead of being executed, much like 'history -L'.

       stop %job|pid ...
               Stops the specified jobs or processes which  are  executing  in  the  back-
               ground.   job  may  be a number, a string, '', '%', '+' or '-' as described
               under Jobs.  There is no default job; saying just 'stop' does not stop  the
               current job.

       suspend Causes  the shell to stop in its tracks, much as if it had been sent a stop
               signal with ^Z.  This is most often used to stop shells started by su(1).

       switch (string)
       case str1:
       endsw   Each case label is successively matched, against the specified string which
               is  first  command and filename expanded.  The file metacharacters '*', '?'
               and '[...]'  may be used in the case labels, which are  variable  expanded.
               If  none  of  the  labels match before a 'default' label is found, then the
               execution begins after the default label.  Each case label and the  default
               label  must  appear at the beginning of a line.  The command breaksw causes
               execution to continue after the endsw.  Otherwise control may fall  through
               case  labels  and default labels as in C.  If no label matches and there is
               no default, execution continues after the endsw.

       telltc (+)
               Lists the values of all terminal capabilities (see termcap(5)).

       termname [terminal type] (+)
               Tests if terminal type (or the current value of TERM if no terminal type is
               given) has an entry in the hosts termcap(5) or terminfo(5) database. Prints
               the terminal type to stdout and returns 0 if an entry is present  otherwise
               returns 1.

       time [command]
               Executes command (which must be a simple command, not an alias, a pipeline,
               a command list or a parenthesized command list) and prints a  time  summary
               as described under the time variable.  If necessary, an extra shell is cre-
               ated to print the time statistic when the command completes.  Without  com-
               mand, prints a time summary for the current shell and its children.

       umask [value]
               Sets the file creation mask to value, which is given in octal.  Common val-
               ues for the mask are 002, giving all access to the group and read and  exe-
               cute access to others, and 022, giving read and execute access to the group
               and others.  Without value, prints the current file creation mask.

       unalias pattern
               Removes all aliases whose names match pattern.  'unalias  *'  thus  removes
               all aliases.  It is not an error for nothing to be unaliased.

       uncomplete pattern (+)
               Removes  all  completions  whose  names match pattern.  'uncomplete *' thus
               removes all completions.  It is not an error for nothing to be uncompleted.

       unhash  Disables  use of the internal hash table to speed location of executed pro-

       universe universe (+)
               Sets the universe to universe.  (Masscomp/RTU only)

       unlimit [-hf] [resource]
               Removes the limitation on resource or, if no  resource  is  specified,  all
               resource  limitations.  With -h, the corresponding hard limits are removed.
               Only the super-user may do this.  Note that unlimit may not  exit  success-
               ful,  since most systems do not allow descriptors to be unlimited.  With -f
               errors are ignored.

       unset pattern
               Removes all variables whose names match pattern, unless they are read-only.
               'unset  *'  thus removes all variables unless they are read-only; this is a
               bad idea.  It is not an error for nothing to be unset.

       unsetenv pattern
               Removes all environment variables whose names match pattern.  'unsetenv  *'
               thus  removes  all environment variables; this is a bad idea.  It is not an
               error for nothing to be unsetenved.

       ver [systype [command]] (+)
               Without arguments, prints SYSTYPE.  With systype, sets SYSTYPE to  systype.
               With  systype  and command, executes command under systype.  systype may be
               'bsd4.3' or 'sys5.3'.  (Domain/OS only)

       wait    The shell waits for all background jobs.  If the shell is  interactive,  an
               interrupt  will disrupt the wait and cause the shell to print the names and
               job numbers of all outstanding jobs.

       warp universe (+)
               Sets the universe to universe.  (Convex/OS only)

       watchlog (+)
               An alternate name for the log builtin command (q.v.).   Available  only  if
               the shell was so compiled; see the version shell variable.

       where command (+)
               Reports  all  known  instances  of command, including aliases, builtins and
               executables in path.

       which command (+)
               Displays the command that will be executed by  the  shell  after  substitu-
               tions, path searching, etc.  The builtin command is just like which(1), but
               it correctly reports tcsh aliases and builtins  and  is  10  to  100  times
               faster.  See also the which-command editor command.

       while (expr)
       end     Executes the commands between the while and the matching end while expr (an
               expression, as described under Expressions) evaluates non-zero.  while  and
               end must appear alone on their input lines.  break and continue may be used
               to terminate or continue the loop prematurely.  If the input is a terminal,
               the user is prompted the first time through the loop as with foreach.

   Special aliases (+)
       If  set,  each of these aliases executes automatically at the indicated time.  They
       are all initially undefined.

       beepcmd Runs when the shell wants to ring the terminal bell.

       cwdcmd  Runs after every change of working directory.  For example, if the user  is
               working on an X window system using xterm(1) and a re-parenting window man-
               ager that supports title bars such as twm(1) and does

                   > alias cwdcmd  'echo -n "^[]2;${HOST}:$cwd ^G"'

               then the shell will change the title of the running xterm(1) to be the name
               of  the  host,  a colon, and the full current working directory.  A fancier
               way to do that is

                   > alias cwdcmd 'echo -n "^[]2;${HOST}:$cwd^G^[]1;${HOST}^G"'

               This will put the hostname and working directory on the title bar but  only
               the hostname in the icon manager menu.

               Note that putting a cd, pushd or popd in cwdcmd may cause an infinite loop.
               It is the author's opinion that anyone doing so will get what they deserve.

       jobcmd  Runs  before each command gets executed, or when the command changes state.
               This is similar to postcmd, but it does not print builtins.

                   > alias jobcmd  'echo -n "^[]2\;\!#:q^G"'

               then executing vi foo.c will put the command string in the xterm title bar.

               Invoked by the run-help editor command.  The command name for which help is
               sought is passed as sole argument.  For example, if one does

                   > alias helpcommand '\!:1 --help'

               then the help display of the command itself will be invoked, using the  GNU
               help  calling  convention.   Currently  there is no easy way to account for
               various calling conventions (e.g., the  customary  Unix  '-h'),  except  by
               using a table of many commands.

               Runs  every tperiod minutes.  This provides a convenient means for checking
               on common but infrequent changes such as new mail.   For  example,  if  one

                   > set tperiod = 30
                   > alias periodic checknews

               then  the  checknews(1)  program runs every 30 minutes.  If periodic is set
               but tperiod is unset or set to 0, periodic behaves like precmd.

       precmd  Runs just before each prompt is printed.  For example, if one does

                   > alias precmd date

               then date(1) runs just before the shell prompts for  each  command.   There
               are  no  limits  on  what precmd can be set to do, but discretion should be

       postcmd Runs before each command gets executed.

                   > alias postcmd  'echo -n "^[]2\;\!#:q^G"'

               then executing vi foo.c will put the command string in the xterm title bar.

       shell   Specifies  the  interpreter  for executable scripts which do not themselves
               specify an interpreter.  The first word should be a full path name  to  the
               desired interpreter (e.g., '/bin/csh' or '/usr/local/bin/tcsh').

   Special shell variables
       The variables described in this section have special meaning to the shell.

       The  shell sets addsuffix, argv, autologout, csubstnonl, command, echo_style, edit,
       gid, group, home, loginsh, oid, path, prompt, prompt2, prompt3, shell, shlvl, tcsh,
       term,  tty,  uid, user and version at startup; they do not change thereafter unless
       changed by the user.  The shell updates cwd, dirstack, owd and status  when  neces-
       sary, and sets logout on logout.

       The shell synchronizes group, home, path, shlvl, term and user with the environment
       variables of the same names: whenever the environment variable  changes  the  shell
       changes  the  corresponding  shell  variable to match (unless the shell variable is
       read-only) and vice versa.  Note that although cwd and PWD have identical meanings,
       they  are  not synchronized in this manner, and that the shell automatically inter-
       converts the different formats of path and PATH.

       addsuffix (+)
               If set, filename completion adds '/' to the end of directories and a  space
               to  the end of normal files when they are matched exactly.  Set by default.

       afsuser (+)
               If set, autologout's autolock feature uses its value instead of  the  local
               username for kerberos authentication.

       ampm (+)
               If set, all times are shown in 12-hour AM/PM format.

       anyerror (+)
               This  variable  selects what is propagated to the value of the status vari-
               able. For more information see  the  description  of  the  status  variable

       argv    The  arguments  to  the  shell.  Positional parameters are taken from argv,
               i.e., '$1' is replaced by '$argv[1]', etc.  Set  by  default,  but  usually
               empty in interactive shells.

       autocorrect (+)
               If  set, the spell-word editor command is invoked automatically before each
               completion attempt.

       autoexpand (+)
               If set, the expand-history editor command is invoked  automatically  before
               each  completion  attempt. If this is set to onlyhistory, then only history
               will be expanded and a second completion will expand filenames.

       autolist (+)
               If set, possibilities are listed after an ambiguous completion.  If set  to
               'ambiguous', possibilities are listed only when no new characters are added
               by completion.

       autologout (+)
               The first word is the number of  minutes  of  inactivity  before  automatic
               logout.   The  optional  second word is the number of minutes of inactivity
               before automatic locking.  When the shell automatically logs out, it prints
               'auto-logout', sets the variable logout to 'automatic' and exits.  When the
               shell automatically locks, the user is required to enter  his  password  to
               continue working.  Five incorrect attempts result in automatic logout.  Set
               to '60' (automatic logout after 60 minutes, and no locking) by  default  in
               login and superuser shells, but not if the shell thinks it is running under
               a window system (i.e., the DISPLAY environment variable is set), the tty is
               a  pseudo-tty (pty) or the shell was not so compiled (see the version shell
               variable).  See also the afsuser and logout shell variables.

       backslash_quote (+)
               If set, backslashes ('\') always quote '\', ''', and '"'.   This  may  make
               complex  quoting  tasks  easier,  but  it can cause syntax errors in csh(1)

       catalog The file name of the message catalog.  If set, tcsh  use  'tcsh.${catalog}'
               as a message catalog instead of default 'tcsh'.

       cdpath  A  list of directories in which cd should search for subdirectories if they
               aren't found in the current directory.

       color   If set, it enables color  display  for  the  builtin  ls-F  and  it  passes
               --color=auto  to  ls.  Alternatively, it can be set to only ls-F or only ls
               to enable color to only one command.  Setting it to nothing  is  equivalent
               to setting it to (ls-F ls).

               If  set,  it enables color escape sequence for NLS message files.  And dis-
               play colorful NLS messages.

       command (+)
               If set, the command which was passed to the shell with the -c flag  (q.v.).

       compat_expr (+)
               If  set, the shell will evaluate expressions right to left, like the origi-
               nal csh.

       complete (+)
               If set to 'enhance', completion 1) ignores case and 2)  considers  periods,
               hyphens  and  underscores  ('.',  '-'  and  '_')  to be word separators and
               hyphens and underscores to be equivalent. If set to 'igncase', the  comple-
               tion becomes case insensitive.

       continue (+)
               If  set to a list of commands, the shell will continue the listed commands,
               instead of starting a new one.

       continue_args (+)
               Same as continue, but the shell will execute:

                   echo 'pwd' $argv > ~/.<cmd>_pause; %<cmd>

       correct (+)
               If set to 'cmd', commands are automatically spelling-corrected.  If set  to
               'complete',  commands  are  automatically  completed.  If set to 'all', the
               entire command line is corrected.

       csubstnonl (+)
               If set, newlines and carriage returns in command substitution are  replaced
               by spaces.  Set by default.

       cwd     The  full pathname of the current directory.  See also the dirstack and owd
               shell variables.

       dextract (+)
               If set, 'pushd +n' extracts the nth  directory  from  the  directory  stack
               rather than rotating it to the top.

       dirsfile (+)
               The  default  location  in which 'dirs -S' and 'dirs -L' look for a history
               file.  If unset, ~/.cshdirs is used.  Because only  ~/.tcshrc  is  normally
               sourced  before ~/.cshdirs, dirsfile should be set in ~/.tcshrc rather than

       dirstack (+)
               An array of all the directories on the directory stack.  '$dirstack[1]'  is
               the  current  working  directory, '$dirstack[2]' the first directory on the
               stack, etc.  Note that the current working directory is '$dirstack[1]'  but
               '=0' in directory stack substitutions, etc.  One can change the stack arbi-
               trarily by setting dirstack, but the first  element  (the  current  working
               directory) is always correct.  See also the cwd and owd shell variables.

       dspmbyte (+)
               Has  an  affect iff 'dspm' is listed as part of the version shell variable.
               If set to 'euc', it enables display and editing  EUC-kanji(Japanese)  code.
               If  set to 'sjis', it enables display and editing Shift-JIS(Japanese) code.
               If set to 'big5', it enables display and editing  Big5(Chinese)  code.   If
               set  to  'utf8', it enables display and editing Utf8(Unicode) code.  If set
               to the following format, it enables display and editing of original  multi-
               byte code format:

                   > set dspmbyte = 0000....(256 bytes)....0000

               The table requires just 256 bytes.  Each character of 256 characters corre-
               sponds (from left to right) to the ASCII codes 0x00, 0x01, ... 0xff.   Each
               character  is  set  to  number  0,1,2 and 3.  Each number has the following
                 0 ... not used for multi-byte characters.
                 1 ... used for the first byte of a multi-byte character.
                 2 ... used for the second byte of a multi-byte character.
                 3 ... used for both the first byte and second byte of a multi-byte  char-

               If  set to '001322', the first character (means 0x00 of the ASCII code) and
               second character (means 0x01 of ASCII code) are set to '0'.   Then,  it  is
               not  used  for  multi-byte  characters.  The 3rd character (0x02) is set to
               '1', indicating that it is used for the first byte of a multi-byte  charac-
               ter.   The  4th  character(0x03) is set '3'.  It is used for both the first
               byte and the second byte of a multi-byte character.  The 5th and 6th  char-
               acters  (0x04,0x05)  are  set to '2', indicating that they are used for the
               second byte of a multi-byte character.

               The GNU fileutils version of ls cannot display multi-byte filenames without
               the  -N ( --literal ) option.   If you are using this version, set the sec-
               ond word of dspmbyte to "ls".  If not, for example, "ls-F -l"  cannot  dis-
               play multi-byte filenames.

               This  variable  can  only be used if KANJI and DSPMBYTE has been defined at
               compile time.

       dunique (+)
               If set, pushd removes any instances of name from the stack  before  pushing
               it onto the stack.

       echo    If  set,  each  command with its arguments is echoed just before it is exe-
               cuted.  For non-builtin  commands  all  expansions  occur  before  echoing.
               Builtin  commands  are  echoed  before  command  and filename substitution,
               because these substitutions are then done selectively.  Set by the -x  com-
               mand line option.

       echo_style (+)
               The style of the echo builtin.  May be set to

               bsd     Don't echo a newline if the first argument is '-n'.
               sysv    Recognize backslashed escape sequences in echo strings.
               both    Recognize  both the '-n' flag and backslashed escape sequences; the
               none    Recognize neither.

               Set by default to the local system default.  The BSD and System  V  options
               are described in the echo(1) man pages on the appropriate systems.

       edit (+)
               If  set,  the  command-line  editor is used.  Set by default in interactive

       ellipsis (+)
               If set, the '%c'/'%.' and '%C' prompt sequences (see the prompt shell vari-
               able)  indicate  skipped  directories  with an ellipsis ('...')  instead of

       fignore (+)
               Lists file name suffixes to be ignored by completion.

       filec   In tcsh, completion is always used and this variable is ignored by default.
               If  edit  is unset, then the traditional csh completion is used.  If set in
               csh, filename completion is used.

       gid (+) The user's real group ID.

       group (+)
               The user's group name.

               If set, the incremental search match (in  i-search-back  and  i-search-fwd)
               and  the  region between the mark and the cursor are highlighted in reverse

               Highlighting requires more frequent terminal writes, which introduces extra
               overhead.  If  you  care  about terminal performance, you may want to leave
               this unset.

               A string value determining the  characters  used  in  History  substitution
               (q.v.).   The first character of its value is used as the history substitu-
               tion character, replacing the default character '!'.  The second  character
               of its value replaces the character '^' in quick substitutions.

       histdup (+)
               Controls  handling  of  duplicate  entries  in the history list.  If set to
               'all' only unique history events are entered in the history list.   If  set
               to  'prev'  and  the last history event is the same as the current command,
               then the current command is not entered in the history.  If set to  'erase'
               and the same event is found in the history list, that old event gets erased
               and the current one gets inserted.  Note that the 'prev' and 'all'  options
               renumber history events so there are no gaps.

       histfile (+)
               The default location in which 'history -S' and 'history -L' look for a his-
               tory file.  If unset, ~/.history is used.  histfile is useful when  sharing
               the same home directory between different machines, or when saving separate
               histories on different  terminals.   Because  only  ~/.tcshrc  is  normally
               sourced  before ~/.history, histfile should be set in ~/.tcshrc rather than

       histlit (+)
               If set, builtin and editor commands and the savehist mechanism use the lit-
               eral  (unexpanded) form of lines in the history list.  See also the toggle-
               literal-history editor command.

       history The first word indicates  the  number  of  history  events  to  save.   The
               optional  second word (+) indicates the format in which history is printed;
               if not given, '%h\t%T\t%R\n' is used.  The format sequences  are  described
               below  under  prompt;  note  the variable meaning of '%R'.  Set to '100' by

       home    Initialized to the home directory of the invoker.  The  filename  expansion
               of '~' refers to this variable.

               If  set  to the empty string or '0' and the input device is a terminal, the
               end-of-file command (usually generated by the user by  typing  '^D'  on  an
               empty  line)  causes the shell to print 'Use "exit" to leave tcsh.' instead
               of exiting.  This prevents the shell from accidentally being killed.   His-
               torically  this  setting exited after 26 successive EOF's to avoid infinite
               loops.  If set to a number n, the shell ignores n - 1  consecutive  end-of-
               files  and  exits  on  the nth.  (+) If unset, '1' is used, i.e., the shell
               exits on a single '^D'.

       implicitcd (+)
               If set, the shell treats a directory name typed as a command as  though  it
               were  a request to change to that directory.  If set to verbose, the change
               of directory is echoed to the standard output.  This behavior is  inhibited
               in non-interactive shell scripts, or for command strings with more than one
               word.  Changing directory takes precedence over executing a like-named com-
               mand,  but it is done after alias substitutions.  Tilde and variable expan-
               sions work as expected.

       inputmode (+)
               If set to 'insert' or 'overwrite', puts the editor into that input mode  at
               the beginning of each line.

       killdup (+)
               Controls  handling  of duplicate entries in the kill ring.  If set to 'all'
               only unique strings are entered in the kill ring.  If set to 'prev' and the
               last  killed string is the same as the current killed string, then the cur-
               rent string is not entered in the ring.  If set to  'erase'  and  the  same
               string  is found in the kill ring, the old string is erased and the current
               one is inserted.

       killring (+)
               Indicates the number of killed strings to keep in memory.  Set to  '30'  by
               default.   If  unset  or set to less than '2', the shell will only keep the
               most recently killed string.  Strings are put in the killring by the editor
               commands  that  delete  (kill)  strings of text, e.g. backward-delete-word,
               kill-line, etc, as well as the copy-region-as-kill command.  The yank  edi-
               tor  command  will  yank  the most recently killed string into the command-
               line, while yank-pop (see Editor commands) can  be  used  to  yank  earlier
               killed strings.

       listflags (+)
               If  set  to  'x', 'a' or 'A', or any combination thereof (e.g., 'xA'), they
               are used as flags to ls-F, making it act like 'ls -xF', 'ls -Fa', 'ls  -FA'
               or a combination (e.g., 'ls -FxA'): 'a' shows all files (even if they start
               with a '.'), 'A' shows all files but '.' and '..',  and  'x'  sorts  across
               instead of down.  If the second word of listflags is set, it is used as the
               path to 'ls(1)'.

       listjobs (+)
               If set, all jobs are listed when a job is suspended.  If set to 'long', the
               listing is in long format.

       listlinks (+)
               If  set, the ls-F builtin command shows the type of file to which each sym-
               bolic link points.

       listmax (+)
               The maximum number of items which the list-choices editor command will list
               without asking first.

       listmaxrows (+)
               The  maximum  number of rows of items which the list-choices editor command
               will list without asking first.

       loginsh (+)
               Set by the shell if it is a login shell.  Setting or unsetting it within  a
               shell has no effect.  See also shlvl.

       logout (+)
               Set  by the shell to 'normal' before a normal logout, 'automatic' before an
               automatic logout, and 'hangup' if the shell was killed by a  hangup  signal
               (see Signal handling).  See also the autologout shell variable.

       mail    The names of the files or directories to check for incoming mail, separated
               by whitespace, and optionally preceded by  a  numeric  word.   Before  each
               prompt,  if  10  minutes have passed since the last check, the shell checks
               each file and says 'You have new mail.'  (or,  if  mail  contains  multiple
               files,  'You  have new mail in name.') if the filesize is greater than zero
               in size and has a modification time greater than its access time.

               If you are in a login shell, then no mail file is reported  unless  it  has
               been modified after the time the shell has started up, to prevent redundant
               notifications.  Most login programs will tell you whether or not  you  have
               mail when you log in.

               If  a file specified in mail is a directory, the shell will count each file
               within that directory as a separate message, and will report  'You  have  n
               mails.'  or 'You have n mails in name.' as appropriate.  This functionality
               is provided primarily for those systems which store mail  in  this  manner,
               such as the Andrew Mail System.

               If the first word of mail is numeric it is taken as a different mail check-
               ing interval, in seconds.

               Under very rare circumstances,  the  shell  may  report  'You  have  mail.'
               instead of 'You have new mail.'

       matchbeep (+)
               If  set  to 'never', completion never beeps.  If set to 'nomatch', it beeps
               only when there is no match.  If set to 'ambiguous', it  beeps  when  there
               are  multiple  matches.   If set to 'notunique', it beeps when there is one
               exact and other longer matches.  If unset, 'ambiguous' is used.

       nobeep (+)
               If set, beeping is completely disabled.  See also visiblebell.

               If set, restrictions are placed on output redirection to insure that  files
               are not accidentally destroyed and that '>>' redirections refer to existing
               files, as described in the Input/output section.

       noding  If set, disable the printing of 'DING!' in the prompt  time  specifiers  at
               the change of hour.

       noglob  If  set,  Filename substitution and Directory stack substitution (q.v.) are
               inhibited.  This is most useful in shell scripts which  do  not  deal  with
               filenames,  or  after  a  list  of  filenames has been obtained and further
               expansions are not desirable.

       nokanji (+)
               If set and the shell supports Kanji (see the version shell variable), it is
               disabled so that the meta key can be used.

               If  set,  a  Filename  substitution  or Directory stack substitution (q.v.)
               which does not match any existing files is left untouched rather than caus-
               ing  an  error.  It is still an error for the substitution to be malformed,
               e.g., 'echo [' still gives an error.

       nostat (+)
               A list of directories (or glob-patterns which match directories; see  File-
               name  substitution) that should not be stat(2)ed during a completion opera-
               tion.  This is usually used to exclude directories which take too much time
               to stat(2), for example /afs.

       notify  If set, the shell announces job completions asynchronously.  The default is
               to present job completions just before printing a prompt.

       oid (+) The user's real organization ID.  (Domain/OS only)

       owd (+) The old working directory, equivalent to the '-' used by cd and pushd.  See
               also the cwd and dirstack shell variables.

       padhour If  set,  enable  the  printing of padding '0' for hours, in 24 and 12 hour
               formats.  E.G.: 07:45:42 vs. 7:45:42

       path    A list of directories in which to look for  executable  commands.   A  null
               word  specifies  the  current directory.  If there is no path variable then
               only full path names will execute.  path is set by  the  shell  at  startup
               from the PATH environment variable or, if PATH does not exist, to a system-
               dependent default something like '(/usr/local/bin  /usr/bsd  /bin  /usr/bin
               .)'.   The  shell  may  put  '.'  first or last in path or omit it entirely
               depending on how it was compiled; see the version shell variable.  A  shell
               which  is given neither the -c nor the -t option hashes the contents of the
               directories in path after reading ~/.tcshrc and each time  path  is  reset.
               If one adds a new command to a directory in path while the shell is active,
               one may need to do a rehash for the shell to find it.

       printexitvalue (+)
               If set and an interactive program exits with a non-zero status,  the  shell
               prints 'Exit status'.

       prompt  The  string which is printed before reading each command from the terminal.
               prompt may include any of the following formatting sequences (+), which are
               replaced by the given information:

               %/  The current working directory.
               %~  The  current  working  directory,  but with one's home directory repre-
                   sented by '~' and other users' home directories represented by  '~user'
                   as per Filename substitution.  '~user' substitution happens only if the
                   shell has already used '~user' in a pathname in the current session.
               %c[[0]n], %.[[0]n]
                   The trailing component of the current working directory, or n  trailing
                   components  if a digit n is given.  If n begins with '0', the number of
                   skipped components precede the  trailing  component(s)  in  the  format
                   '/<skipped>trailing'.   If  the ellipsis shell variable is set, skipped
                   components  are  represented  by  an  ellipsis  so  the  whole  becomes
                   '...trailing'.   '~' substitution is done as in '%~' above, but the '~'
                   component is ignored when counting trailing components.
               %C  Like %c, but without '~' substitution.
               %h, %!, !
                   The current history event number.
               %M  The full hostname.
               %m  The hostname up to the first '.'.
               %S (%s)
                   Start (stop) standout mode.
               %B (%b)
                   Start (stop) boldfacing mode.
               %U (%u)
                   Start (stop) underline mode.
               %t, %@
                   The time of day in 12-hour AM/PM format.
               %T  Like '%t', but in 24-hour format (but see the ampm shell variable).
               %p  The 'precise' time of day in 12-hour AM/PM format, with seconds.
               %P  Like '%p', but in 24-hour format (but see the ampm shell variable).
               \c  c is parsed as in bindkey.
               ^c  c is parsed as in bindkey.
               %%  A single '%'.
               %n  The user name.
               %j  The number of jobs.
               %d  The weekday in 'Day' format.
               %D  The day in 'dd' format.
               %w  The month in 'Mon' format.
               %W  The month in 'mm' format.
               %y  The year in 'yy' format.
               %Y  The year in 'yyyy' format.
               %l  The shell's tty.
               %L  Clears from the end of the prompt to end of the display or the  end  of
                   the line.
               %$  Expands  the  shell  or environment variable name immediately after the
               %#  '>' (or the first character of the promptchars shell variable) for nor-
                   mal  users,  '#' (or the second character of promptchars) for the supe-
                   Includes string as a literal escape sequence.  It should be  used  only
                   to  change terminal attributes and should not move the cursor location.
                   This cannot be the last sequence in prompt.
               %?  The return code of the command executed just before the prompt.
               %R  In prompt2, the status  of  the  parser.   In  prompt3,  the  corrected
                   string.  In history, the history string.

               '%B',  '%S',  '%U'  and  '%{string%}' are available in only eight-bit-clean
               shells; see the version shell variable.

               The bold, standout and underline sequences are often used to distinguish  a
               superuser shell.  For example,

                   > set prompt = "%m [%h] %B[%@]%b [%/] you rang? "
                   tut [37] [2:54pm] [/usr/accts/sys] you rang? _

               If  '%t',  '%@',  '%T',  '%p', or '%P' is used, and noding is not set, then
               print 'DING!' on the change of hour (i.e, ':00'  minutes)  instead  of  the
               actual time.

               Set by default to '%# ' in interactive shells.

       prompt2 (+)
               The  string with which to prompt in while and foreach loops and after lines
               ending in '\'.  The same format sequences may be used as in prompt  (q.v.);
               note the variable meaning of '%R'.  Set by default to '%R? ' in interactive

       prompt3 (+)
               The string with which to prompt when confirming automatic spelling  correc-
               tion.   The same format sequences may be used as in prompt (q.v.); note the
               variable meaning of '%R'.  Set by default to 'CORRECT>%R  (y|n|e|a)?  '  in
               interactive shells.

       promptchars (+)
               If  set  (to  a  two-character string), the '%#' formatting sequence in the
               prompt shell variable is replaced with the first character for normal users
               and the second character for the superuser.

       pushdtohome (+)
               If set, pushd without arguments does 'pushd ~', like cd.

       pushdsilent (+)
               If set, pushd and popd do not print the directory stack.

       recexact (+)
               If  set,  completion  completes on an exact match even if a longer match is

       recognize_only_executables (+)
               If set, command listing displays only files  in  the  path  that  are  exe-
               cutable.  Slow.

       rmstar (+)
               If set, the user is prompted before 'rm *' is executed.

       rprompt (+)
               The string to print on the right-hand side of the screen (after the command
               input) when the prompt is being displayed on the left.  It  recognizes  the
               same  formatting characters as prompt.  It will automatically disappear and
               reappear as necessary, to ensure that command  input  isn't  obscured,  and
               will appear only if the prompt, command input, and itself will fit together
               on the first line.  If edit isn't set, then rprompt will be  printed  after
               the prompt and before the command input.

       savedirs (+)
               If  set, the shell does 'dirs -S' before exiting.  If the first word is set
               to a number, at most that many directory stack entries are saved.

               If set, the shell does 'history -S' before exiting.  If the first  word  is
               set  to  a  number, at most that many lines are saved.  (The number must be
               less than or equal to history.)  If the second word is set to 'merge',  the
               history  list is merged with the existing history file instead of replacing
               it (if there is one) and sorted by time stamp and the  most  recent  events
               are retained.  (+)

       sched (+)
               The  format  in which the sched builtin command prints scheduled events; if
               not given, '%h\t%T\t%R\n' is used.   The  format  sequences  are  described
               above under prompt; note the variable meaning of '%R'.

       shell   The  file  in  which  the shell resides.  This is used in forking shells to
               interpret files which have execute bits set, but which are  not  executable
               by  the  system.   (See  the description of Builtin and non-builtin command
               execution.)  Initialized to the (system-dependent) home of the shell.

       shlvl (+)
               The number of nested shells.   Reset  to  1  in  login  shells.   See  also

       status  The  exit  status from the last command or backquote expansion, or any com-
               mand in a pipeline is propagated to status.  (This is also the default  csh
               behavior.)   This default does not match what POSIX mandates (to return the
               status of the last command only). To match the POSIX behavior, you need  to
               unset anyerror.

               If  the anyerror variable is unset, the exit status of a pipeline is deter-
               mined only from the last command in the pipeline, and the exit status of  a
               backquote expansion is not propagated to status.

               If  a  command  terminated  abnormally,  then  0200 is added to the status.
               Builtin commands which fail return exit status '1', all other builtin  com-
               mands return status '0'.

       symlinks (+)
               Can be set to several different values to control symbolic link ('symlink')

               If set to 'chase', whenever the current directory changes  to  a  directory
               containing  a  symbolic link, it is expanded to the real name of the direc-
               tory to which the link points.  This does not  work  for  the  user's  home
               directory; this is a bug.

               If  set to 'ignore', the shell tries to construct a current directory rela-
               tive to the current directory before the link was crossed.  This means that
               cding through a symbolic link and then 'cd ..'ing returns one to the origi-
               nal directory.  This affects only builtin commands and filename completion.

               If  set  to  'expand',  the  shell  tries to fix symbolic links by actually
               expanding arguments which look like path names.  This affects any  command,
               not just builtins.  Unfortunately, this does not work for hard-to-recognize
               filenames, such as those embedded in command  options.   Expansion  may  be
               prevented  by  quoting.  While this setting is usually the most convenient,
               it is sometimes misleading and sometimes confusing when it fails to  recog-
               nize an argument which should be expanded.  A compromise is to use 'ignore'
               and use the editor command normalize-path (bound by default to  ^X-n)  when

               Some examples are in order.  First, let's set up some play directories:

                   > cd /tmp
                   > mkdir from from/src to
                   > ln -s from/src to/dst

               Here's the behavior with symlinks unset,

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               here's the behavior with symlinks set to 'chase',

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               here's the behavior with symlinks set to 'ignore',

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               and here's the behavior with symlinks set to 'expand'.

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd
                   > cd /tmp/to/dst; echo $cwd
                   > cd ".."; echo $cwd
                   > /bin/echo ..
                   > /bin/echo ".."

               Note  that 'expand' expansion 1) works just like 'ignore' for builtins like
               cd, 2) is prevented by quoting, and 3) happens before filenames are  passed
               to non-builtin commands.

       tcsh (+)
               The  version  number of the shell in the format 'R.VV.PP', where 'R' is the
               major release number, 'VV' the current version and 'PP' the patchlevel.

       term    The terminal type.  Usually set in ~/.login as described under Startup  and

       time    If  set  to  a  number, then the time builtin (q.v.) executes automatically
               after each command which takes more than that many CPU seconds.   If  there
               is  a second word, it is used as a format string for the output of the time
               builtin.  (u) The following sequences may be used in the format string:

               %U  The time the process spent in user mode in cpu seconds.
               %S  The time the process spent in kernel mode in cpu seconds.
               %E  The elapsed (wall clock) time in seconds.
               %P  The CPU percentage computed as (%U + %S) / %E.
               %W  Number of times the process was swapped.
               %X  The average amount in (shared) text space used in Kbytes.
               %D  The average amount in (unshared) data/stack space used in Kbytes.
               %K  The total space used (%X + %D) in Kbytes.
               %M  The maximum memory the process had in use at any time in Kbytes.
               %F  The number of major page faults (page needed to be brought from  disk).
               %R  The number of minor page faults.
               %I  The number of input operations.
               %O  The number of output operations.
               %r  The number of socket messages received.
               %s  The number of socket messages sent.
               %k  The number of signals received.
               %w  The number of voluntary context switches (waits).
               %c  The number of involuntary context switches.

               Only the first four sequences are supported on systems without BSD resource
               limit functions.  The default time format is '%Uu %Ss %E %P %X+%Dk  %I+%Oio
               %Fpf+%Ww' for systems that support resource usage reporting and '%Uu %Ss %E
               %P' for systems that do not.

               Under Sequent's DYNIX/ptx, %X, %D, %K, %r and %s are not available, but the
               following additional sequences are:

               %Y  The number of system calls performed.
               %Z  The number of pages which are zero-filled on demand.
               %i  The  number of times a process's resident set size was increased by the
               %d  The number of times a process's resident set size was decreased by  the
               %l  The number of read system calls performed.
               %m  The number of write system calls performed.
               %p  The number of reads from raw disk devices.
               %q  The number of writes to raw disk devices.

               and the default time format is '%Uu %Ss %E %P %I+%Oio %Fpf+%Ww'.  Note that
               the CPU percentage can be higher than 100% on multi-processors.

       tperiod (+)
               The period, in minutes, between executions of the periodic special alias.

       tty (+) The name of the tty, or empty if not attached to one.

       uid (+) The user's real user ID.

       user    The user's login name.

       verbose If set, causes the words of each command to be printed, after history  sub-
               stitution (if any).  Set by the -v command line option.

       version (+)
               The  version  ID stamp.  It contains the shell's version number (see tcsh),
               origin, release date, vendor, operating system  and  machine  (see  VENDOR,
               OSTYPE  and  MACHTYPE) and a comma-separated list of options which were set
               at compile time.  Options which are set by default in the distribution  are

               8b    The shell is eight bit clean; default
               7b    The shell is not eight bit clean
               wide  The shell is multibyte encoding clean (like UTF-8)
               nls   The system's NLS is used; default for systems with NLS
               lf    Login   shells   execute   /etc/csh.login  before  instead  of  after
                     /etc/csh.cshrc and ~/.login before instead  of  after  ~/.tcshrc  and
               dl    '.' is put last in path for security; default
               nd    '.' is omitted from path for security
               vi    vi-style editing is the default rather than emacs
               dtr   Login shells drop DTR when exiting
               bye   bye is a synonym for logout and log is an alternate name for watchlog
               al    autologout is enabled; default
               kan   Kanji is used if appropriate according to locale settings, unless the
                     nokanji shell variable is set
               sm    The system's malloc(3) is used
               hb    The  '#!<program> <args>' convention is emulated when executing shell
               ng    The newgrp builtin is available
               rh    The shell attempts to set the REMOTEHOST environment variable
               afs   The shell verifies your password with the kerberos  server  if  local
                     authentication  fails.   The  afsuser  shell  variable or the AFSUSER
                     environment variable override your local username if set.

               An administrator may enter additional strings to  indicate  differences  in
               the local version.

       visiblebell (+)
               If  set,  a  screen  flash  is used rather than the audible bell.  See also

       watch (+)
               A list of user/terminal pairs to watch for logins and logouts.   If  either
               the  user  is  'any'  all terminals are watched for the given user and vice
               versa.  Setting watch to '(any any)' watches all users and terminals.   For

                   set watch = (george ttyd1 any console $user any)

               reports  activity  of  the user 'george' on ttyd1, any user on the console,
               and oneself (or a trespasser) on any terminal.

               Logins and logouts are checked every 10 minutes by default, but  the  first
               word  of  watch can be set to a number to check every so many minutes.  For

                   set watch = (1 any any)

               reports any login/logout once every minute.  For  the  impatient,  the  log
               builtin  command  triggers  a watch report at any time.  All current logins
               are reported (as with the log builtin) when watch is first set.

               The who shell variable controls the format of watch reports.

       who (+) The format string for watch messages.  The following sequences are replaced
               by the given information:

               %n  The name of the user who logged in/out.
               %a  The  observed  action,  i.e.,  'logged  on',  'logged off' or 'replaced
                   olduser on'.
               %l  The terminal (tty) on which the user logged in/out.
               %M  The full hostname of the remote host, or 'local'  if  the  login/logout
                   was from the local host.
               %m  The  hostname of the remote host up to the first '.'.  The full name is
                   printed if it is an IP address or an X Window System display.

               %M and %m are available on only systems that store the remote  hostname  in
               /etc/utmp.   If  unset, '%n has %a %l from %m.' is used, or '%n has %a %l.'
               on systems which don't store the remote hostname.

       wordchars (+)
               A list of non-alphanumeric characters to be considered part of  a  word  by
               the   forward-word,   backward-word   etc.,  editor  commands.   If  unset,
               '*?_-.[]~=' is used.

       AFSUSER (+)
               Equivalent to the afsuser shell variable.

       COLUMNS The number of columns in the terminal.  See Terminal management.

       DISPLAY Used by X Window System (see X(1)).  If set, the shell does not set autolo-
               gout (q.v.).

       EDITOR  The pathname to a default editor.  See also the VISUAL environment variable
               and the run-fg-editor editor command.

       GROUP (+)
               Equivalent to the group shell variable.

       HOME    Equivalent to the home shell variable.

       HOST (+)
               Initialized to the name of the machine on which the shell  is  running,  as
               determined by the gethostname(2) system call.

       HOSTTYPE (+)
               Initialized to the type of machine on which the shell is running, as deter-
               mined at compile time.  This variable is obsolete and will be removed in  a
               future version.

       HPATH (+)
               A  colon-separated list of directories in which the run-help editor command
               looks for command documentation.

       LANG    Gives the preferred character environment.  See Native Language System sup-

               If set, only ctype character handling is changed.  See Native Language Sys-
               tem support.

       LINES   The number of lines in the terminal.  See Terminal management.

               The format of this variable is reminiscent of the termcap(5) file format; a
               colon-separated  list of expressions of the form "xx=string", where "xx" is
               a  two-character  variable  name.   The  variables  with  their  associated
               defaults are:

                   no   0      Normal (non-filename) text
                   fi   0      Regular file
                   di   01;34  Directory
                   ln   01;36  Symbolic link
                   pi   33     Named pipe (FIFO)
                   so   01;35  Socket
                   do   01;35  Door
                   bd   01;33  Block device
                   cd   01;32  Character device
                   ex   01;32  Executable file
                   mi   (none) Missing file (defaults to fi)
                   or   (none) Orphaned symbolic link (defaults to ln)
                   lc   ^[[    Left code
                   rc   m      Right code
                   ec   (none) End code (replaces lc+no+rc)

               You need to include only the variables you want to change from the default.

               File names can also be colorized based  on  filename  extension.   This  is
               specified  in  the  LS_COLORS variable using the syntax "*ext=string".  For
               example, using ISO 6429 codes, to color all C-language  source  files  blue
               you  would  specify  "*.c=34".   This would color all files ending in .c in
               blue (34) color.

               Control characters can be written either in C-style-escaped notation, or in
               stty-like  ^-notation.   The  C-style  notation adds ^[ for Escape, _ for a
               normal space character, and ? for Delete.  In addition, the ^[ escape char-
               acter can be used to override the default interpretation of ^[, ^, : and =.

               Each file will be written as <lc> <color-code> <rc>  <filename>  <ec>.   If
               the  <ec>  code  is  undefined,  the  sequence  <lc> <no> <rc> will be used
               instead.  This is generally more convenient to use, but less general.   The
               left,  right  and  end  codes are provided so you don't have to type common
               parts over and over again and to support weird terminals; you  will  gener-
               ally  not  need to change them at all unless your terminal does not use ISO
               6429 color sequences but a different system.

               If your terminal does use ISO 6429 color codes, you can  compose  the  type
               codes  (i.e.,  all except the lc, rc, and ec codes) from numerical commands
               separated by semicolons.  The most common commands are:

                       0   to restore default color
                       1   for brighter colors
                       4   for underlined text
                       5   for flashing text
                       30  for black foreground
                       31  for red foreground
                       32  for green foreground
                       33  for yellow (or brown) foreground
                       34  for blue foreground
                       35  for purple foreground
                       36  for cyan foreground
                       37  for white (or gray) foreground
                       40  for black background
                       41  for red background
                       42  for green background
                       43  for yellow (or brown) background
                       44  for blue background
                       45  for purple background
                       46  for cyan background
                       47  for white (or gray) background

               Not all commands will work on all systems or display devices.

               A few terminal programs do not recognize the default end code properly.  If
               all  text gets colorized after you do a directory listing, try changing the
               no and fi codes from 0 to the numerical codes for your standard  fore-  and
               background colors.

       MACHTYPE (+)
               The  machine type (microprocessor class or machine model), as determined at
               compile time.

       NOREBIND (+)
               If set, printable characters are not rebound to  self-insert-command.   See
               Native Language System support.

       OSTYPE (+)
               The operating system, as determined at compile time.

       PATH    A  colon-separated  list  of  directories in which to look for executables.
               Equivalent to the path shell variable, but in a different format.

       PWD (+) Equivalent to the cwd shell variable, but not synchronized to  it;  updated
               only after an actual directory change.

       REMOTEHOST (+)
               The  host  from  which the user has logged in remotely, if this is the case
               and the shell is able to determine it.  Set only if the shell was  so  com-
               piled; see the version shell variable.

       SHLVL (+)
               Equivalent to the shlvl shell variable.

       SYSTYPE (+)
               The current system type.  (Domain/OS only)

       TERM    Equivalent to the term shell variable.

       TERMCAP The terminal capability string.  See Terminal management.

       USER    Equivalent to the user shell variable.

       VENDOR (+)
               The vendor, as determined at compile time.

       VISUAL  The pathname to a default full-screen editor.  See also the EDITOR environ-
               ment variable and the run-fg-editor editor command.

       /etc/csh.cshrc  Read first  by  every  shell.   ConvexOS,  Stellix  and  Intel  use
                       /etc/cshrc and NeXTs use /etc/cshrc.std.  A/UX, AMIX, Cray and IRIX
                       have no equivalent in csh(1), but read this file  in  tcsh  anyway.
                       Solaris  2.x  does  not have it either, but tcsh reads /etc/.cshrc.
       /etc/csh.login  Read by login shells after /etc/csh.cshrc.  ConvexOS,  Stellix  and
                       Intel  use  /etc/login,  NeXTs use /etc/login.std, Solaris 2.x uses
                       /etc/.login and A/UX, AMIX, Cray and IRIX use /etc/cshrc.
       ~/.tcshrc (+)   Read by every shell after /etc/csh.cshrc or its equivalent.
       ~/.cshrc        Read  by  every  shell,   if   ~/.tcshrc   doesn't   exist,   after
                       /etc/csh.cshrc  or its equivalent.  This manual uses '~/.tcshrc' to
                       mean '~/.tcshrc or, if ~/.tcshrc is not found, ~/.cshrc'.
       ~/.history      Read by login shells after ~/.tcshrc if savehist is  set,  but  see
                       also histfile.
       ~/.login        Read  by login shells after ~/.tcshrc or ~/.history.  The shell may
                       be compiled to read ~/.login before instead of after ~/.tcshrc  and
                       ~/.history; see the version shell variable.
       ~/.cshdirs (+)  Read  by  login  shells  after ~/.login if savedirs is set, but see
                       also dirsfile.
       /etc/csh.logout Read by login shells at logout.  ConvexOS, Stellix  and  Intel  use
                       /etc/logout  and  NeXTs  use /etc/logout.std.  A/UX, AMIX, Cray and
                       IRIX have no equivalent in csh(1), but read this file in tcsh  any-
                       way.   Solaris  2.x  does  not  have  it  either,  but  tcsh  reads
                       /etc/.logout.  (+)
       ~/.logout       Read by login shells at logout after /etc/csh.logout or its equiva-
       /bin/sh         Used to interpret shell scripts not starting with a '#'.
       /tmp/sh*        Temporary file for '<<'.
       /etc/passwd     Source of home directories for '~name' substitutions.

       The  order in which startup files are read may differ if the shell was so compiled;
       see Startup and shutdown and the version shell variable.

       This manual describes tcsh as a single entity, but experienced  csh(1)  users  will
       want to pay special attention to tcsh's new features.

       A  command-line  editor, which supports GNU Emacs or vi(1)-style key bindings.  See
       The command-line editor and Editor commands.

       Programmable, interactive word completion and listing.  See Completion and  listing
       and the complete and uncomplete builtin commands.

       Spelling correction (q.v.) of filenames, commands and variables.

       Editor  commands (q.v.) which perform other useful functions in the middle of typed
       commands, including documentation lookup (run-help), quick editor restarting  (run-
       fg-editor) and command resolution (which-command).

       An  enhanced  history mechanism.  Events in the history list are time-stamped.  See
       also the history command and its associated shell variables, the previously undocu-
       mented '#' event specifier and new modifiers under History substitution, the *-his-
       tory, history-search-*, i-search-*, vi-search-* and  toggle-literal-history  editor
       commands and the histlit shell variable.

       Enhanced  directory  parsing and directory stack handling.  See the cd, pushd, popd
       and dirs commands and their associated shell variables, the description  of  Direc-
       tory  stack  substitution,  the  dirstack, owd and symlinks shell variables and the
       normalize-command and normalize-path editor commands.

       Negation in glob-patterns.  See Filename substitution.

       New File inquiry operators (q.v.) and a filetest builtin which uses them.

       A variety of Automatic,  periodic  and  timed  events  (q.v.)  including  scheduled
       events,  special aliases, automatic logout and terminal locking, command timing and
       watching for logins and logouts.

       Support for the Native Language System (see Native  Language  System  support),  OS
       variant  features  (see  OS  variant support and the echo_style shell variable) and
       system-dependent file locations (see FILES).

       Extensive terminal-management capabilities.  See Terminal management.

       New builtin commands including builtins, hup, ls-F,  newgrp,  printenv,  which  and
       where (q.v.).

       New  variables that make useful information easily available to the shell.  See the
       gid, loginsh, oid, shlvl, tcsh, tty, uid and version shell variables and the  HOST,
       REMOTEHOST, VENDOR, OSTYPE and MACHTYPE environment variables.

       A  new  syntax  for including useful information in the prompt string (see prompt).
       and special prompts for loops and spelling correction (see prompt2 and prompt3).

       Read-only variables.  See Variable substitution.

       When a suspended command is restarted, the shell prints the directory it started in
       if  this  is  different  from the current directory.  This can be misleading (i.e.,
       wrong) as the job may have changed directories internally.

       Shell builtin functions are not stoppable/restartable.  Command  sequences  of  the
       form  'a  ;  b ; c' are also not handled gracefully when stopping is attempted.  If
       you suspend 'b', the shell will then immediately execute 'c'.  This  is  especially
       noticeable  if  this  expansion  results  from  an alias.  It suffices to place the
       sequence of commands in ()'s to force it to a subshell, i.e., '( a ; b ; c )'.

       Control over tty output after processes are started is primitive; perhaps this will
       inspire  someone to work on a good virtual terminal interface.  In a virtual termi-
       nal interface much more interesting things could be done with output control.

       Alias substitution is most often used to clumsily simulate shell procedures;  shell
       procedures should be provided rather than aliases.

       Commands  within  loops  are  not  placed  in the history list.  Control structures
       should be parsed rather than being recognized as  built-in  commands.   This  would
       allow  control  commands  to be placed anywhere, to be combined with '|', and to be
       used with '&' and ';' metasyntax.

       foreach doesn't ignore here documents when looking for its end.

       It should be possible to use the ':' modifiers on the output of  command  substitu-

       The screen update for lines longer than the screen width is very poor if the termi-
       nal cannot move the cursor up (i.e., terminal type 'dumb').

       HPATH and NOREBIND don't need to be environment variables.

       Glob-patterns which do not use '?', '*' or '[]' or which use '{}' or  '~'  are  not
       negated correctly.

       The  single-command  form  of  if does output redirection even if the expression is
       false and the command is not executed.

       ls-F includes file identification characters when sorting filenames  and  does  not
       handle control characters in filenames well.  It cannot be interrupted.

       Command  substitution  supports multiple commands and conditions, but not cycles or
       backward gotos.

       Report bugs at, preferably with fixes.  If  you  want  to  help
       maintain  and  test  tcsh,  send mail to tcsh-request AT with the text 'sub-
       scribe tcsh' on a line by itself in the body.

       In 1964, DEC produced the PDP-6.  The PDP-10 was a later re-implementation.  It was
       re-christened the DECsystem-10 in 1970 or so when DEC brought out the second model,
       the KI10.

       TENEX was created at Bolt, Beranek & Newman (a Cambridge, Massachusetts think tank)
       in  1972  as  an experiment in demand-paged virtual memory operating systems.  They
       built a new pager for the DEC PDP-10 and created the OS to  go  with  it.   It  was
       extremely successful in academia.

       In 1975, DEC brought out a new model of the PDP-10, the KL10; they intended to have
       only a version of TENEX, which they had licensed from BBN, for the new  box.   They
       called  their  version  TOPS-20  (their  capitalization  is trademarked).  A lot of
       TOPS-10 users ('The OPerating System for PDP-10') objected; thus  DEC  found  them-
       selves  supporting  two  incompatible  systems on the same hardware--but then there
       were 6 on the PDP-11!

       TENEX, and TOPS-20 to version 3, had command completion via a user-code-level  sub-
       routine  library  called ULTCMD.  With version 3, DEC moved all that capability and
       more into the monitor ('kernel' for you Unix types), accessed by  the  COMND%  JSYS
       ('Jump to SYStem' instruction, the supervisor call mechanism [are my IBM roots also

       The creator of tcsh was impressed by this feature and several others of  TENEX  and
       TOPS-20, and created a version of csh which mimicked them.

       The system limits argument lists to ARG_MAX characters.

       The  number  of arguments to a command which involves filename expansion is limited
       to 1/6th the number of characters allowed in an argument list.

       Command substitutions may substitute no more characters  than  are  allowed  in  an
       argument list.

       To  detect looping, the shell restricts the number of alias substitutions on a sin-
       gle line to 20.

       csh(1), emacs(1), ls(1), newgrp(1), sh(1),  setpath(1),  stty(1),  su(1),  tset(1),
       vi(1),  x(1),  access(2),  execve(2),  fork(2),  killpg(2),  pipe(2), setrlimit(2),
       sigvec(2), stat(2), umask(2), vfork(2), wait(2), malloc(3),  setlocale(3),  tty(4),
       a.out(5), termcap(5), environ(7), termio(7), Introduction to the C Shell

       This manual documents tcsh 6.17.00 (Astron) 2009-07-10.

       William Joy
         Original author of csh(1)
       J.E. Kulp, IIASA, Laxenburg, Austria
         Job control and directory stack features
       Ken Greer, HP Labs, 1981
         File name completion
       Mike Ellis, Fairchild, 1983
         Command name recognition/completion
       Paul Placeway, Ohio State CIS Dept., 1983-1993
         Command  line  editor,  prompt  routines,  new glob syntax and numerous fixes and
       Karl Kleinpaste, CCI 1983-4
         Special aliases, directory stack extraction stuff, login/logout watch,  scheduled
         events, and the idea of the new prompt format
       Rayan Zachariassen, University of Toronto, 1984
         ls-F and which builtins and numerous bug fixes, modifications and speedups
       Chris Kingsley, Caltech
         Fast storage allocator routines
       Chris Grevstad, TRW, 1987
         Incorporated 4.3BSD csh into tcsh
       Christos S. Zoulas, Cornell U. EE Dept., 1987-94
         Ports  to  HPUX,  SVR2 and SVR3, a SysV version of getwd.c, SHORT_STRINGS support
         and a new version of sh.glob.c
       James J Dempsey, BBN, and Paul Placeway, OSU, 1988
         A/UX port
       Daniel Long, NNSC, 1988
       Patrick Wolfe, Kuck and Associates, Inc., 1988
         vi mode cleanup
       David C Lawrence, Rensselaer Polytechnic Institute, 1989
         autolist and ambiguous completion listing
       Alec Wolman, DEC, 1989
         Newlines in the prompt
       Matt Landau, BBN, 1989
       Ray Moody, Purdue Physics, 1989
         Magic space bar history expansion
       Mordechai ????, Intel, 1989
         printprompt() fixes and additions
       Kazuhiro Honda, Dept. of Computer Science, Keio University, 1989
         Automatic spelling correction and prompt3
       Per Hedeland, Ellemtel, Sweden, 1990-
         Various bugfixes, improvements and manual updates
       Hans J. Albertsson (Sun Sweden)
         ampm, settc and telltc
       Michael Bloom
         Interrupt handling fixes
       Michael Fine, Digital Equipment Corp
         Extended key support
       Eric Schnoebelen, Convex, 1990
         Convex support, lots of csh bug fixes, save and restore of directory stack
       Ron Flax, Apple, 1990
         A/UX 2.0 (re)port
       Dan Oscarsson, LTH Sweden, 1990
         NLS support and simulated NLS support for non NLS sites, fixes
       Johan Widen, SICS Sweden, 1990
         shlvl, Mach support, correct-line, 8-bit printing
       Matt Day, Sanyo Icon, 1990
         POSIX termio support, SysV limit fixes
       Jaap Vermeulen, Sequent, 1990-91
         Vi mode fixes, expand-line, window change fixes, Symmetry port
       Martin Boyer, Institut de recherche d'Hydro-Quebec, 1991
         autolist beeping options, modified the history search to  search  for  the  whole
         string from the beginning of the line to the cursor.
       Scott Krotz, Motorola, 1991
         Minix port
       David Dawes, Sydney U. Australia, Physics Dept., 1991
         SVR4 job control fixes
       Jose Sousa, Interactive Systems Corp., 1991
         Extended vi fixes and vi delete command
       Marc Horowitz, MIT, 1991
         ANSIfication fixes, new exec hashing code, imake fixes, where
       Bruce Sterling Woodcock, sterling AT, 1991-1995
         ETA  and Pyramid port, Makefile and lint fixes, ignoreeof=n addition, and various
         other portability changes and bug fixes
       Jeff Fink, 1992
         complete-word-fwd and complete-word-back
       Harry C. Pulley, 1992
         Coherent port
       Andy Phillips, Mullard Space Science Lab U.K., 1992
         VMS-POSIX port
       Beto Appleton, IBM Corp., 1992
         Walking process group fixes, csh bug fixes, POSIX file tests, POSIX SIGHUP
       Scott Bolte, Cray Computer Corp., 1992
         CSOS port
       Kaveh R. Ghazi, Rutgers University, 1992
         Tek, m88k, Titan and Masscomp ports and fixes.  Added autoconf support.
       Mark Linderman, Cornell University, 1992
         OS/2 port
       Mika Liljeberg, liljeber AT kruuna.FI, 1992
         Linux port
       Tim P. Starrin, NASA Langley Research Center Operations, 1993
         Read-only variables
       Dave Schweisguth, Yale University, 1993-4
         New man page and tcsh.man2html
       Larry Schwimmer, Stanford University, 1993
         AFS and HESIOD patches
       Luke Mewburn, RMIT University, 1994-6
         Enhanced directory printing in prompt, added ellipsis and rprompt.
       Edward Hutchins, Silicon Graphics Inc., 1996
         Added implicit cd.
       Martin Kraemer, 1997
         Ported to Siemens Nixdorf EBCDIC machine
       Amol Deshpande, Microsoft, 1997
         Ported to WIN32 (Windows/95 and Windows/NT); wrote all the  missing  library  and
         message catalog code to interface to Windows.
       Taga Nayuta, 1998
         Color ls additions.

       Bryan Dunlap, Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve Romig, Diana Smet-
       ters, Bob Sutterfield, Mark Verber, Elizabeth Zwicky and all the  other  people  at
       Ohio State for suggestions and encouragement

       All  the  people on the net, for putting up with, reporting bugs in, and suggesting
       new additions to each and every version

       Richard M. Alderson III, for writing the 'T in tcsh' section

Astron 6.17.00                   10 July 2009                          TCSH(1)

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