bg - phpMan

Command: man perldoc info search(apropos)  


BASH_BUILTINS(1)                                              BASH_BUILTINS(1)



NAME
       bash,  :, ., [, alias, bg, bind, break, builtin, caller, cd, command, compgen, com-
       plete, compopt, continue, declare, dirs, disown, echo, enable,  eval,  exec,  exit,
       export,  false,  fc,  fg,  getopts,  hash,  help,  history, jobs, kill, let, local,
       logout, mapfile, popd, printf, pushd, pwd,  read,  readonly,  return,  set,  shift,
       shopt, source, suspend, test, times, trap, true, type, typeset, ulimit, umask, una-
       lias, unset, wait - bash built-in commands, see bash(1)

BASH BUILTIN COMMANDS
       Unless otherwise noted, each builtin command documented in this section as  accept-
       ing  options  preceded  by  - accepts -- to signify the end of the options.  The :,
       true, false, and test builtins do not accept options and do not treat -- specially.
       The exit, logout, break, continue, let, and shift builtins accept and process argu-
       ments beginning with - without requiring --.  Other builtins that accept  arguments
       but  are not specified as accepting options interpret arguments beginning with - as
       invalid options and require -- to prevent this interpretation.
       : [arguments]
              No effect; the command does nothing beyond expanding arguments and  perform-
              ing any specified redirections.  A zero exit code is returned.

        .  filename [arguments]
       source filename [arguments]
              Read and execute commands from filename in the current shell environment and
              return the exit status of the last command executed from filename.  If file-
              name  does  not  contain  a  slash,  file names in PATH are used to find the
              directory containing filename.  The file searched for in PATH  need  not  be
              executable.   When  bash  is  not  in  posix  mode, the current directory is
              searched if no file is found in PATH.  If the sourcepath option to the shopt
              builtin  command  is turned off, the PATH is not searched.  If any arguments
              are supplied, they become the positional parameters when  filename  is  exe-
              cuted.   Otherwise the positional parameters are unchanged.  The return sta-
              tus is the status of the last command exited within the script (0 if no com-
              mands are executed), and false if filename is not found or cannot be read.

       alias [-p] [name[=value] ...]
              Alias  with no arguments or with the -p option prints the list of aliases in
              the form alias name=value on standard output.  When arguments are  supplied,
              an alias is defined for each name whose value is given.  A trailing space in
              value causes the next word to be checked for  alias  substitution  when  the
              alias is expanded.  For each name in the argument list for which no value is
              supplied, the name and value of the alias is printed.   Alias  returns  true
              unless a name is given for which no alias has been defined.

       bg [jobspec ...]
              Resume  each  suspended  job  jobspec  in  the background, as if it had been
              started with &.  If jobspec is not present, the shell's notion of  the  cur-
              rent  job is used.  bg jobspec returns 0 unless run when job control is dis-
              abled or, when run with job control enabled, any specified jobspec  was  not
              found or was started without job control.

       bind [-m keymap] [-lpsvPSV]
       bind [-m keymap] [-q function] [-u function] [-r keyseq]
       bind [-m keymap] -f filename
       bind [-m keymap] -x keyseq:shell-command
       bind [-m keymap] keyseq:function-name
       bind readline-command
              Display current readline key and function bindings, bind a key sequence to a
              readline function or macro, or set a  readline  variable.   Each  non-option
              argument  is  a  command as it would appear in .inputrc, but each binding or
              command  must  be  passed  as  a  separate  argument;   e.g.,   '"\C-x\C-r":
              re-read-init-file'.  Options, if supplied, have the following meanings:
              -m keymap
                     Use  keymap  as the keymap to be affected by the subsequent bindings.
                     Acceptable  keymap  names  are  emacs,  emacs-standard,   emacs-meta,
                     emacs-ctlx, vi, vi-move, vi-command, and vi-insert.  vi is equivalent
                     to vi-command; emacs is equivalent to emacs-standard.
              -l     List the names of all readline functions.
              -p     Display readline function names and bindings in such a way that  they
                     can be re-read.
              -P     List current readline function names and bindings.
              -s     Display  readline  key sequences bound to macros and the strings they
                     output in such a way that they can be re-read.
              -S     Display readline key sequences bound to macros and the  strings  they
                     output.
              -v     Display  readline  variable  names and values in such a way that they
                     can be re-read.
              -V     List current readline variable names and values.
              -f filename
                     Read key bindings from filename.
              -q function
                     Query about which keys invoke the named function.
              -u function
                     Unbind all keys bound to the named function.
              -r keyseq
                     Remove any current binding for keyseq.
              -x keyseq:shell-command
                     Cause shell-command to be executed whenever keyseq is entered.   When
                     shell-command  is executed, the shell sets the READLINE_LINE variable
                     to the contents of the readline line buffer  and  the  READLINE_POINT
                     variable to the current location of the insertion point.  If the exe-
                     cuted command changes the value of READLINE_LINE  or  READLINE_POINT,
                     those new values will be reflected in the editing state.

              The  return  value  is  0 unless an unrecognized option is given or an error
              occurred.

       break [n]
              Exit from within a for, while, until, or select loop.  If  n  is  specified,
              break  n levels.  n must be >= 1.  If n is greater than the number of enclos-
              ing loops, all enclosing loops are exited.  The  return  value  is  non-zero
              when n is <= 0; Otherwise, break returns 0 value.

       builtin shell-builtin [arguments]
              Execute  the  specified  shell builtin, passing it arguments, and return its
              exit status.  This is useful when defining a function whose name is the same
              as  a  shell  builtin, retaining the functionality of the builtin within the
              function.  The cd builtin is commonly redefined this way.  The return status
              is false if shell-builtin is not a shell builtin command.

       caller [expr]
              Returns  the  context  of  any active subroutine call (a shell function or a
              script executed with the . or source builtins.  Without  expr,  caller  dis-
              plays  the  line  number and source filename of the current subroutine call.
              If a non-negative integer is supplied as expr, caller displays the line num-
              ber,  subroutine name, and source file corresponding to that position in the
              current execution call stack.  This extra information may be used, for exam-
              ple,  to  print  a  stack  trace.  The current frame is frame 0.  The return
              value is 0 unless the shell is not executing a subroutine call or expr  does
              not correspond to a valid position in the call stack.

       cd [-L|-P] [dir]
              Change  the current directory to dir.  The variable HOME is the default dir.
              The variable CDPATH defines the search path  for  the  directory  containing
              dir.  Alternative directory names in CDPATH are separated by a colon (:).  A
              null directory name in CDPATH is the same as the  current  directory,  i.e.,
              ''.''.   If  dir  begins  with  a slash (/), then CDPATH is not used. The -P
              option says to use the physical directory  structure  instead  of  following
              symbolic  links  (see also the -P option to the set builtin command); the -L
              option forces symbolic links to be followed.  An argument of - is equivalent
              to  $OLDPWD.   If a non-empty directory name from CDPATH is used, or if - is
              the first argument, and the directory change  is  successful,  the  absolute
              pathname  of  the  new  working directory is written to the standard output.
              The return value is true if the directory was  successfully  changed;  false
              otherwise.

       command [-pVv] command [arg ...]
              Run  command  with  args  suppressing the normal shell function lookup. Only
              builtin commands or commands found in the PATH  are  executed.   If  the  -p
              option  is  given, the search for command is performed using a default value
              for PATH that is guaranteed to find  all  of  the  standard  utilities.   If
              either the -V or -v option is supplied, a description of command is printed.
              The -v option causes a single word indicating the command or file name  used
              to  invoke  command  to  be displayed; the -V option produces a more verbose
              description.  If the -V or -v option is supplied, the exit status  is  0  if
              command was found, and 1 if not.  If neither option is supplied and an error
              occurred or command cannot be found, the exit status is 127.  Otherwise, the
              exit status of the command builtin is the exit status of command.

       compgen [option] [word]
              Generate  possible  completion  matches  for  word according to the options,
              which may be any option accepted by the complete builtin with the  exception
              of  -p and -r, and write the matches to the standard output.  When using the
              -F or -C options, the various shell variables set by the  programmable  com-
              pletion facilities, while available, will not have useful values.

              The matches will be generated in the same way as if the programmable comple-
              tion code had generated them directly from a completion  specification  with
              the  same flags.  If word is specified, only those completions matching word
              will be displayed.

              The return value is true unless an invalid option is supplied, or no matches
              were generated.

       complete  [-abcdefgjksuv]  [-o  comp-option]  [-DE]  [-A  action]  [-G globpat] [-W
       wordlist] [-F function] [-C command]
              [-X filterpat] [-P prefix] [-S suffix] name [name ...]
       complete -pr [-DE] [name ...]
              Specify how arguments to each name should be completed.  If the -p option is
              supplied, or if no options are supplied, existing completion  specifications
              are  printed in a way that allows them to be reused as input.  The -r option
              removes a completion specification for each name, or, if no names  are  sup-
              plied,  all  completion  specifications.   The  -D option indicates that the
              remaining options and actions should apply to the ''default''  command  com-
              pletion;  that is, completion attempted on a command for which no completion
              has previously been defined.  The -E option  indicates  that  the  remaining
              options  and  actions should apply to ''empty'' command completion; that is,
              completion attempted on a blank line.

              The process of applying these completion specifications when word completion
              is attempted is described above under Programmable Completion.

              Other  options, if specified, have the following meanings.  The arguments to
              the -G, -W, and -X options (and, if necessary, the -P and -S options) should
              be  quoted  to  protect  them  from expansion before the complete builtin is
              invoked.
              -o comp-option
                      The comp-option controls several aspects of the compspec's  behavior
                      beyond the simple generation of completions.  comp-option may be one
                      of:
                      bashdefault
                              Perform the rest of the  default  bash  completions  if  the
                              compspec generates no matches.
                      default Use  readline's  default filename completion if the compspec
                              generates no matches.
                      dirnames
                              Perform directory name completion if the compspec  generates
                              no matches.
                      filenames
                              Tell  readline  that the compspec generates filenames, so it
                              can perform any filename-specific processing (like adding  a
                              slash  to  directory  names,  quoting special characters, or
                              suppressing trailing spaces).   Intended  to  be  used  with
                              shell functions.
                      nospace Tell  readline  not to append a space (the default) to words
                              completed at the end of the line.
                      plusdirs
                              After any matches defined by  the  compspec  are  generated,
                              directory  name  completion is attempted and any matches are
                              added to the results of the other actions.
              -A action
                      The action may be one of the following to generate a list of  possi-
                      ble completions:
                      alias   Alias names.  May also be specified as -a.
                      arrayvar
                              Array variable names.
                      binding Readline key binding names.
                      builtin Names  of  shell builtin commands.  May also be specified as
                              -b.
                      command Command names.  May also be specified as -c.
                      directory
                              Directory names.  May also be specified as -d.
                      disabled
                              Names of disabled shell builtins.
                      enabled Names of enabled shell builtins.
                      export  Names of exported shell variables.  May also be specified as
                              -e.
                      file    File names.  May also be specified as -f.
                      function
                              Names of shell functions.
                      group   Group names.  May also be specified as -g.
                      helptopic
                              Help topics as accepted by the help builtin.
                      hostname
                              Hostnames,  as taken from the file specified by the HOSTFILE
                              shell variable.
                      job     Job names, if job control is active.  May also be  specified
                              as -j.
                      keyword Shell reserved words.  May also be specified as -k.
                      running Names of running jobs, if job control is active.
                      service Service names.  May also be specified as -s.
                      setopt  Valid arguments for the -o option to the set builtin.
                      shopt   Shell option names as accepted by the shopt builtin.
                      signal  Signal names.
                      stopped Names of stopped jobs, if job control is active.
                      user    User names.  May also be specified as -u.
                      variable
                              Names  of all shell variables.  May also be specified as -v.
              -G globpat
                      The pathname expansion pattern globpat is expanded to  generate  the
                      possible completions.
              -W wordlist
                      The  wordlist is split using the characters in the IFS special vari-
                      able as delimiters, and each resultant word is expanded.  The possi-
                      ble  completions  are  the members of the resultant list which match
                      the word being completed.
              -C command
                      command is executed in a subshell environment,  and  its  output  is
                      used as the possible completions.
              -F function
                      The  shell  function function is executed in the current shell envi-
                      ronment.  When it finishes, the possible completions  are  retrieved
                      from the value of the COMPREPLY array variable.
              -X filterpat
                      filterpat  is  a  pattern  as  used  for  pathname expansion.  It is
                      applied to the list of possible completions generated by the preced-
                      ing options and arguments, and each completion matching filterpat is
                      removed from the list.  A leading ! in filterpat  negates  the  pat-
                      tern;  in  this  case,  any  completion  not  matching  filterpat is
                      removed.
              -P prefix
                      prefix is added at the beginning of each possible  completion  after
                      all other options have been applied.
              -S suffix
                      suffix  is  appended  to  each  possible  completion after all other
                      options have been applied.

              The return value is true unless an invalid option  is  supplied,  an  option
              other  than -p or -r is supplied without a name argument, an attempt is made
              to remove a completion specification for a name for which  no  specification
              exists, or an error occurs adding a completion specification.

       compopt [-o option] [-DE] [+o option] [name]
              Modify completion options for each name according to the options, or for the
              currently-execution completion if no names are supplied.  If no options  are
              given,  display  the completion options for each name or the current comple-
              tion.  The possible values of  option  are  those  valid  for  the  complete
              builtin described above.  The -D option indicates that the remaining options
              should apply to the ''default''  command  completion;  that  is,  completion
              attempted  on a command for which no completion has previously been defined.
              The -E option indicates that the remaining options should apply to ''empty''
              command completion; that is, completion attempted on a blank line.

       The  return  value is true unless an invalid option is supplied, an attempt is made
       to modify the options for a name for which no completion specification  exists,  or
       an output error occurs.

       continue [n]
              Resume  the  next  iteration  of  the enclosing for, while, until, or select
              loop.  If n is specified, resume at the nth enclosing loop.  n must be >=  1.
              If  n is greater than the number of enclosing loops, the last enclosing loop
              (the ''top-level'' loop) is resumed.  When continue is  executed  inside  of
              loop,  the  return  value  is  non-zero  when  n is <= 0; Otherwise, continue
              returns 0 value. When continue is executed outside of loop, the return value
              is 0.

       declare [-aAfFilrtux] [-p] [name[=value] ...]
       typeset [-aAfFilrtux] [-p] [name[=value] ...]
              Declare  variables  and/or give them attributes.  If no names are given then
              display the values of variables.  The -p option will display the  attributes
              and  values  of  each name.  When -p is used with name arguments, additional
              options are ignored.  When -p is supplied without name  arguments,  it  will
              display  the  attributes  and  values of all variables having the attributes
              specified by the additional options.  If no other options are supplied  with
              -p,  declare  will display the attributes and values of all shell variables.
              The -f option will restrict the display to shell functions.  The  -F  option
              inhibits  the  display  of  function definitions; only the function name and
              attributes are printed.  If the  extdebug  shell  option  is  enabled  using
              shopt,  the  source  file name and line number where the function is defined
              are displayed as well.  The -F option implies -f.  The following options can
              be  used  to restrict output to variables with the specified attribute or to
              give variables attributes:
              -a     Each name is an indexed array variable (see Arrays above).
              -A     Each name is an associative array variable (see Arrays above).
              -f     Use function names only.
              -i     The variable is treated as an  integer;  arithmetic  evaluation  (see
                     ARITHMETIC  EVALUATION  above)  is  performed  when  the  variable is
                     assigned a value.
              -l     When the variable is assigned a value, all upper-case characters  are
                     converted to lower-case.  The upper-case attribute is disabled.
              -r     Make  names  readonly.  These names cannot then be assigned values by
                     subsequent assignment statements or unset.
              -t     Give each name the trace attribute.   Traced  functions  inherit  the
                     DEBUG  and  RETURN traps from the calling shell.  The trace attribute
                     has no special meaning for variables.
              -u     When the variable is assigned a value, all lower-case characters  are
                     converted to upper-case.  The lower-case attribute is disabled.
              -x     Mark names for export to subsequent commands via the environment.

              Using  '+'  instead  of '-' turns off the attribute instead, with the excep-
              tions that +a may not be used to destroy an array variable and +r  will  not
              remove  the  readonly  attribute.   When used in a function, makes each name
              local, as with the local command.  If a variable name is followed by =value,
              the  value of the variable is set to value.  The return value is 0 unless an
              invalid option is encountered, an attempt is made to define a function using
              ''-f foo=bar'', an attempt is made to assign a value to a readonly variable,
              an attempt is made to assign a value to an array variable without using  the
              compound  assignment  syntax  (see  Arrays above), one of the names is not a
              valid shell variable name, an attempt is made to turn  off  readonly  status
              for  a readonly variable, an attempt is made to turn off array status for an
              array variable, or an attempt is made to  display  a  non-existent  function
              with -f.

       dirs [+n] [-n] [-cplv]
              Without options, displays the list of currently remembered directories.  The
              default display is on a  single  line  with  directory  names  separated  by
              spaces.   Directories are added to the list with the pushd command; the popd
              command removes entries from the list.
              +n     Displays the nth entry counting from the left of the  list  shown  by
                     dirs when invoked without options, starting with zero.
              -n     Displays  the  nth entry counting from the right of the list shown by
                     dirs when invoked without options, starting with zero.
              -c     Clears the directory stack by deleting all of the entries.
              -l     Produces a longer listing; the default listing format uses a tilde to
                     denote the home directory.
              -p     Print the directory stack with one entry per line.
              -v     Print  the  directory  stack  with one entry per line, prefixing each
                     entry with its index in the stack.

              The return value is 0 unless an invalid option  is  supplied  or  n  indexes
              beyond the end of the directory stack.

       disown [-ar] [-h] [jobspec ...]
              Without  options, each jobspec is removed from the table of active jobs.  If
              jobspec is not present, and neither -a  nor  -r  is  supplied,  the  shell's
              notion  of the current job is used.  If the -h option is given, each jobspec
              is not removed from the table, but is marked so that SIGHUP is not  sent  to
              the  job if the shell receives a SIGHUP.  If no jobspec is present, and nei-
              ther the -a nor the -r option is supplied, the current job is used.   If  no
              jobspec  is supplied, the -a option means to remove or mark all jobs; the -r
              option without a jobspec argument restricts operation to running jobs.   The
              return value is 0 unless a jobspec does not specify a valid job.

       echo [-neE] [arg ...]
              Output  the  args,  separated  by spaces, followed by a newline.  The return
              status is always 0.  If -n is specified, the trailing newline is suppressed.
              If the -e option is given, interpretation of the following backslash-escaped
              characters is enabled.  The -E option disables the interpretation  of  these
              escape  characters,  even  on systems where they are interpreted by default.
              The xpg_echo shell option may be used to dynamically  determine  whether  or
              not  echo  expands these escape characters by default.  echo does not inter-
              pret -- to mean the end of options.  echo interprets  the  following  escape
              sequences:
              \a     alert (bell)
              \b     backspace
              \c     suppress further output
              \e     an escape character
              \f     form feed
              \n     new line
              \r     carriage return
              \t     horizontal tab
              \v     vertical tab
              \\     backslash
              \0nnn  the  eight-bit  character whose value is the octal value nnn (zero to
                     three octal digits)
              \xHH   the eight-bit character whose value is the hexadecimal value HH  (one
                     or two hex digits)

       enable [-a] [-dnps] [-f filename] [name ...]
              Enable  and  disable  builtin  shell commands.  Disabling a builtin allows a
              disk command which has the same name as a shell builtin to be executed with-
              out  specifying a full pathname, even though the shell normally searches for
              builtins before disk commands.  If -n is used, each name is disabled; other-
              wise,  names are enabled.  For example, to use the test binary found via the
              PATH instead of the shell builtin version, run ''enable -n test''.   The  -f
              option  means  to load the new builtin command name from shared object file-
              name, on systems that support dynamic loading.  The -d option will delete  a
              builtin  previously  loaded  with -f.  If no name arguments are given, or if
              the -p option is supplied, a list of shell builtins  is  printed.   With  no
              other option arguments, the list consists of all enabled shell builtins.  If
              -n is supplied, only disabled builtins are printed.  If -a is supplied,  the
              list  printed  includes  all  builtins, with an indication of whether or not
              each is enabled.  If -s is supplied, the output is restricted to  the  POSIX
              special  builtins.   The  return  value  is  0  unless a name is not a shell
              builtin or there is an error loading a new builtin from a shared object.

       eval [arg ...]
              The args are read and concatenated together into  a  single  command.   This
              command  is  then  read  and  executed  by the shell, and its exit status is
              returned as the value of eval.  If there are no args,  or  only  null  argu-
              ments, eval returns 0.

       exec [-cl] [-a name] [command [arguments]]
              If  command is specified, it replaces the shell.  No new process is created.
              The arguments become the arguments to command.  If the  -l  option  is  sup-
              plied,  the  shell  places  a  dash  at the beginning of the zeroth argument
              passed to command.  This is what login(1) does.  The -c option  causes  com-
              mand to be executed with an empty environment.  If -a is supplied, the shell
              passes name as the zeroth argument to the executed command.  If command can-
              not  be  executed for some reason, a non-interactive shell exits, unless the
              shell option execfail is enabled, in which  case  it  returns  failure.   An
              interactive  shell  returns failure if the file cannot be executed.  If com-
              mand is not specified, any redirections take effect in  the  current  shell,
              and  the  return  status  is 0.  If there is a redirection error, the return
              status is 1.

       exit [n]
              Cause the shell to exit with a status of n.  If n is omitted, the exit  sta-
              tus is that of the last command executed.  A trap on EXIT is executed before
              the shell terminates.

       export [-fn] [name[=word]] ...
       export -p
              The supplied names are marked for automatic export  to  the  environment  of
              subsequently  executed commands.  If the -f option is given, the names refer
              to functions.  If no names are given, or if the -p  option  is  supplied,  a
              list of all names that are exported in this shell is printed.  The -n option
              causes the export property to be removed from each name.  If a variable name
              is  followed  by  =word,  the  value of the variable is set to word.  export
              returns an exit status of 0 unless an invalid option is encountered, one  of
              the  names is not a valid shell variable name, or -f is supplied with a name
              that is not a function.

       fc [-e ename] [-lnr] [first] [last]
       fc -s [pat=rep] [cmd]
              Fix Command.  In the first form, a range of commands from first to  last  is
              selected from the history list.  First and last may be specified as a string
              (to locate the last command beginning with that string) or as a  number  (an
              index  into  the  history list, where a negative number is used as an offset
              from the current command number).  If last is not specified it is set to the
              current  command  for listing (so that ''fc -l -10'' prints the last 10 com-
              mands) and to first otherwise.  If first is not specified it is set  to  the
              previous command for editing and -16 for listing.

              The  -n  option  suppresses the command numbers when listing.  The -r option
              reverses the order of the commands.  If the -l option is given, the commands
              are  listed  on  standard  output.   Otherwise, the editor given by ename is
              invoked on a file containing those commands.  If ename  is  not  given,  the
              value  of  the FCEDIT variable is used, and the value of EDITOR if FCEDIT is
              not set.  If neither variable is set, is used.  When  editing  is  complete,
              the edited commands are echoed and executed.

              In  the  second  form,  command is re-executed after each instance of pat is
              replaced by rep.  A useful alias to use with this is ''r="fc -s"'', so  that
              typing ''r cc'' runs the last command beginning with ''cc'' and typing ''r''
              re-executes the last command.

              If the first form is used, the return value is 0 unless an invalid option is
              encountered  or first or last specify history lines out of range.  If the -e
              option is supplied, the return value is the value of the last  command  exe-
              cuted or failure if an error occurs with the temporary file of commands.  If
              the second form is used, the return status is that of  the  command  re-exe-
              cuted,  unless  cmd  does not specify a valid history line, in which case fc
              returns failure.

       fg [jobspec]
              Resume jobspec in the foreground, and make it the current job.   If  jobspec
              is  not  present, the shell's notion of the current job is used.  The return
              value is that of the command placed into the foreground, or failure  if  run
              when  job control is disabled or, when run with job control enabled, if job-
              spec does not specify a valid job  or  jobspec  specifies  a  job  that  was
              started without job control.

       getopts optstring name [args]
              getopts  is  used  by shell procedures to parse positional parameters.  opt-
              string contains the option characters to be recognized; if  a  character  is
              followed  by  a  colon,  the  option  is expected to have an argument, which
              should be separated from it by white space.  The  colon  and  question  mark
              characters  may  not be used as option characters.  Each time it is invoked,
              getopts places the next option in the shell variable name, initializing name
              if  it  does  not  exist, and the index of the next argument to be processed
              into the variable OPTIND.  OPTIND is initialized to 1 each time the shell or
              a  shell  script  is  invoked.  When an option requires an argument, getopts
              places that argument into the variable OPTARG.  The  shell  does  not  reset
              OPTIND  automatically;  it  must be manually reset between multiple calls to
              getopts within the same shell invocation if a new set of parameters is to be
              used.

              When  the  end  of options is encountered, getopts exits with a return value
              greater than zero.  OPTIND is set to the index of the first non-option argu-
              ment, and name is set to ?.

              getopts normally parses the positional parameters, but if more arguments are
              given in args, getopts parses those instead.

              getopts can report errors in two ways.  If the first character of  optstring
              is  a colon, silent error reporting is used.  In normal operation diagnostic
              messages are printed when invalid options or missing  option  arguments  are
              encountered.   If the variable OPTERR is set to 0, no error messages will be
              displayed, even if the first character of optstring is not a colon.

              If an invalid option is seen, getopts places ? into name and, if not silent,
              prints an error message and unsets OPTARG.  If getopts is silent, the option
              character found is placed in OPTARG and no diagnostic message is printed.

              If a required argument is not found, and getopts is not silent,  a  question
              mark  (?)  is  placed  in name, OPTARG is unset, and a diagnostic message is
              printed.  If getopts is silent, then a colon  (:)  is  placed  in  name  and
              OPTARG is set to the option character found.

              getopts  returns  true if an option, specified or unspecified, is found.  It
              returns false if the end of options is encountered or an error occurs.

       hash [-lr] [-p filename] [-dt] [name]
              For each name, the full file name of the command is determined by  searching
              the  directories  in $PATH and remembered.  If the -p option is supplied, no
              path search is performed, and filename is used as the full file name of  the
              command.  The -r option causes the shell to forget all remembered locations.
              The -d option causes the shell to forget the  remembered  location  of  each
              name.   If  the  -t option is supplied, the full pathname to which each name
              corresponds is printed.  If multiple name arguments are  supplied  with  -t,
              the  name  is printed before the hashed full pathname.  The -l option causes
              output to be displayed in a format that may be reused as input.  If no argu-
              ments  are  given,  or  if only -l is supplied, information about remembered
              commands is printed.  The return status is true unless a name is  not  found
              or an invalid option is supplied.

       help [-dms] [pattern]
              Display  helpful  information  about builtin commands.  If pattern is speci-
              fied, help gives detailed help on all commands matching  pattern;  otherwise
              help for all the builtins and shell control structures is printed.
              -d     Display a short description of each pattern
              -m     Display the description of each pattern in a manpage-like format
              -s     Display only a short usage synopsis for each pattern
       The return status is 0 unless no command matches pattern.

       history [n]
       history -c
       history -d offset
       history -anrw [filename]
       history -p arg [arg ...]
       history -s arg [arg ...]
              With  no options, display the command history list with line numbers.  Lines
              listed with a * have been modified.  An argument of n lists only the last  n
              lines.  If the shell variable HISTTIMEFORMAT is set and not null, it is used
              as a format string for strftime(3) to display the time stamp associated with
              each  displayed  history entry.  No intervening blank is printed between the
              formatted time stamp and the history line.  If filename is supplied,  it  is
              used as the name of the history file; if not, the value of HISTFILE is used.
              Options, if supplied, have the following meanings:
              -c     Clear the history list by deleting all the entries.
              -d offset
                     Delete the history entry at position offset.
              -a     Append the ''new'' history lines (history  lines  entered  since  the
                     beginning of the current bash session) to the history file.
              -n     Read  the  history  lines not already read from the history file into
                     the current history list.  These are lines appended  to  the  history
                     file since the beginning of the current bash session.
              -r     Read  the  contents  of  the history file and use them as the current
                     history.
              -w     Write the current history to the history file, overwriting  the  his-
                     tory file's contents.
              -p     Perform  history  substitution  on the following args and display the
                     result on the standard output.  Does not store  the  results  in  the
                     history  list.   Each  arg  must  be quoted to disable normal history
                     expansion.
              -s     Store the args in the history list as a single entry.  The last  com-
                     mand in the history list is removed before the args are added.

              If the HISTTIMEFORMAT variable is set, the time stamp information associated
              with each history entry is written to the history file, marked with the his-
              tory comment character.  When the history file is read, lines beginning with
              the history comment character followed immediately by  a  digit  are  inter-
              preted  as  timestamps for the previous history line.  The return value is 0
              unless an invalid option is encountered, an error occurs  while  reading  or
              writing  the  history  file, an invalid offset is supplied as an argument to
              -d, or the history expansion supplied as an argument to -p fails.

       jobs [-lnprs] [ jobspec ... ]
       jobs -x command [ args ... ]
              The first form lists the active jobs.  The options have the following  mean-
              ings:
              -l     List process IDs in addition to the normal information.
              -p     List only the process ID of the job's process group leader.
              -n     Display  information  only  about jobs that have changed status since
                     the user was last notified of their status.
              -r     Restrict output to running jobs.
              -s     Restrict output to stopped jobs.

              If jobspec is given, output is restricted to  information  about  that  job.
              The return status is 0 unless an invalid option is encountered or an invalid
              jobspec is supplied.

              If the -x option is supplied, jobs replaces any jobspec found in command  or
              args  with  the corresponding process group ID, and executes command passing
              it args, returning its exit status.

       kill [-s sigspec | -n signum | -sigspec] [pid | jobspec] ...
       kill -l [sigspec | exit_status]
              Send the signal named by sigspec or signum to the processes named by pid  or
              jobspec.   sigspec  is either a case-insensitive signal name such as SIGKILL
              (with or without the SIG prefix) or a signal number; signum is a signal num-
              ber.  If sigspec is not present, then SIGTERM is assumed.  An argument of -l
              lists the signal names.  If any arguments are supplied when -l is given, the
              names  of  the  signals  corresponding  to the arguments are listed, and the
              return status is 0.  The exit_status argument to -l is a  number  specifying
              either  a signal number or the exit status of a process terminated by a sig-
              nal.  kill returns true if at least one signal  was  successfully  sent,  or
              false if an error occurs or an invalid option is encountered.

       let arg [arg ...]
              Each arg is an arithmetic expression to be evaluated (see ARITHMETIC EVALUA-
              TION above).  If the last arg evaluates to 0, let returns 1; 0  is  returned
              otherwise.

       local [option] [name[=value] ...]
              For  each  argument,  a  local  variable named name is created, and assigned
              value.  The option can be any of the  options  accepted  by  declare.   When
              local is used within a function, it causes the variable name to have a visi-
              ble scope restricted to that function and its children.  With  no  operands,
              local  writes  a  list  of local variables to the standard output.  It is an
              error to use local when not within a  function.   The  return  status  is  0
              unless  local  is  used  outside a function, an invalid name is supplied, or
              name is a readonly variable.

       logout Exit a login shell.

       mapfile [-n count] [-O origin] [-s count] [-t] [-u fd] [-C callback]  [-c  quantum]
       [array]
       readarray [-n count] [-O origin] [-s count] [-t] [-u fd] [-C callback] [-c quantum]
       [array]
              Read lines from the standard input into the indexed array variable array, or
              from  file descriptor fd if the -u option is supplied.  The variable MAPFILE
              is the default array.  Options, if supplied, have the following meanings:
              -n     Copy at most count lines.  If count is 0, all lines are copied.
              -O     Begin assigning to array at index origin.  The default index is 0.
              -s     Discard the first count lines read.
              -t     Remove a trailing newline from each line read.
              -u     Read lines from file descriptor fd instead of the standard input.
              -C     Evaluate callback each time quantum lines are read.   The  -c  option
                     specifies quantum.
              -c     Specify the number of lines read between each call to callback.

              If  -C  is specified without -c, the default quantum is 5000.  When callback
              is evaluated, it is supplied the index of  the  next  array  element  to  be
              assigned as an additional argument.  callback is evaluated after the line is
              read but before the array element is assigned.

              If not supplied with an explicit origin, mapfile  will  clear  array  before
              assigning to it.

              mapfile  returns successfully unless an invalid option or option argument is
              supplied, array is invalid or unassignable, or if array is  not  an  indexed
              array.

       popd [-n] [+n] [-n]
              Removes  entries  from  the directory stack.  With no arguments, removes the
              top directory from the stack, and performs a cd to the  new  top  directory.
              Arguments, if supplied, have the following meanings:
              -n     Suppresses  the  normal change of directory when removing directories
                     from the stack, so that only the stack is manipulated.
              +n     Removes the nth entry counting from the left of  the  list  shown  by
                     dirs, starting with zero.  For example: ''popd +0'' removes the first
                     directory, ''popd +1'' the second.
              -n     Removes the nth entry counting from the right of the  list  shown  by
                     dirs,  starting with zero.  For example: ''popd -0'' removes the last
                     directory, ''popd -1'' the next to last.

              If the popd command is successful, a dirs is  performed  as  well,  and  the
              return status is 0.  popd returns false if an invalid option is encountered,
              the directory stack is empty, a non-existent directory stack entry is speci-
              fied, or the directory change fails.

       printf [-v var] format [arguments]
              Write  the  formatted  arguments to the standard output under the control of
              the format.  The format is a character string which contains three types  of
              objects: plain characters, which are simply copied to standard output, char-
              acter escape sequences, which are converted and copied to the standard  out-
              put,  and  format  specifications, each of which causes printing of the next
              successive argument.  In addition to  the  standard  printf(1)  formats,  %b
              causes  printf  to  expand  backslash  escape sequences in the corresponding
              argument (except that \c terminates output, backslashes in \',  \",  and  \?
              are  not removed, and octal escapes beginning with \0 may contain up to four
              digits), and %q causes printf to output the corresponding argument in a for-
              mat that can be reused as shell input.

              The  -v  option  causes the output to be assigned to the variable var rather
              than being printed to the standard output.

              The format is reused as necessary to consume all of the arguments.   If  the
              format  requires more arguments than are supplied, the extra format specifi-
              cations behave as if a zero value or null string, as appropriate,  had  been
              supplied.  The return value is zero on success, non-zero on failure.

       pushd [-n] [+n] [-n]
       pushd [-n] [dir]
              Adds  a  directory  to the top of the directory stack, or rotates the stack,
              making the new top of the stack the  current  working  directory.   With  no
              arguments,  exchanges  the  top  two  directories  and returns 0, unless the
              directory stack is empty.  Arguments, if supplied, have the following  mean-
              ings:
              -n     Suppresses  the normal change of directory when adding directories to
                     the stack, so that only the stack is manipulated.
              +n     Rotates the stack so that the nth directory (counting from  the  left
                     of the list shown by dirs, starting with zero) is at the top.
              -n     Rotates  the stack so that the nth directory (counting from the right
                     of the list shown by dirs, starting with zero) is at the top.
              dir    Adds dir to the directory stack at the top, making it the new current
                     working directory.

              If  the  pushd  command  is successful, a dirs is performed as well.  If the
              first form is used, pushd returns 0 unless the cd to dir  fails.   With  the
              second  form,  pushd  returns  0 unless the directory stack is empty, a non-
              existent directory stack element is specified, or the  directory  change  to
              the specified new current directory fails.

       pwd [-LP]
              Print  the absolute pathname of the current working directory.  The pathname
              printed contains no symbolic links if the -P option is supplied  or  the  -o
              physical  option to the set builtin command is enabled.  If the -L option is
              used, the pathname printed may contain symbolic links.  The return status is
              0  unless an error occurs while reading the name of the current directory or
              an invalid option is supplied.

       read [-ers] [-a aname] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-t
       timeout] [-u fd] [name ...]
              One line is read from the standard input, or from  the  file  descriptor  fd
              supplied  as an argument to the -u option, and the first word is assigned to
              the first name, the second word to the second name, and so on, with leftover
              words  and their intervening separators assigned to the last name.  If there
              are fewer words read from the input stream than names, the  remaining  names
              are assigned empty values.  The characters in IFS are used to split the line
              into words.  The backslash character (\) may be used to remove  any  special
              meaning  for the next character read and for line continuation.  Options, if
              supplied, have the following meanings:
              -a aname
                     The words are assigned to sequential indices of  the  array  variable
                     aname,  starting  at  0.   aname  is  unset before any new values are
                     assigned.  Other name arguments are ignored.
              -d delim
                     The first character of delim is used to  terminate  the  input  line,
                     rather than newline.
              -e     If  the standard input is coming from a terminal, readline (see READ-
                     LINE above) is used to obtain the line.  Readline  uses  the  current
                     (or  default, if line editing was not previously active) editing set-
                     tings.
              -i text
                     If readline is being used to read the line, text is placed  into  the
                     editing buffer before editing begins.
              -n nchars
                     read  returns after reading nchars characters rather than waiting for
                     a complete line of input, but honor a delimiter if fewer than  nchars
                     characters are read before the delimiter.
              -N nchars
                     read  returns  after  reading  exactly  nchars characters rather than
                     waiting for a complete line of input, unless EOF  is  encountered  or
                     read  times  out.   Delimiter characters encountered in the input are
                     not treated specially and do not cause read to  return  until  nchars
                     characters are read.
              -p prompt
                     Display  prompt on standard error, without a trailing newline, before
                     attempting to read any input.  The prompt is displayed only if  input
                     is coming from a terminal.
              -r     Backslash does not act as an escape character.  The backslash is con-
                     sidered to be part of the line.  In particular,  a  backslash-newline
                     pair may not be used as a line continuation.
              -s     Silent  mode.  If input is coming from a terminal, characters are not
                     echoed.
              -t timeout
                     Cause read to time out and return failure if a complete line of input
                     is  not read within timeout seconds.  timeout may be a decimal number
                     with a fractional portion following the decimal point.   This  option
                     is  only effective if read is reading input from a terminal, pipe, or
                     other special file; it has no effect when reading from regular files.
                     If  timeout  is  0, read returns success if input is available on the
                     specified file descriptor, failure otherwise.   The  exit  status  is
                     greater than 128 if the timeout is exceeded.
              -u fd  Read input from file descriptor fd.

              If  no  names are supplied, the line read is assigned to the variable REPLY.
              The return code is zero, unless end-of-file is encountered, read  times  out
              (in  which  case  the  return  code is greater than 128), or an invalid file
              descriptor is supplied as the argument to -u.

       readonly [-aApf] [name[=word] ...]
              The given names are marked readonly; the values of these names  may  not  be
              changed  by  subsequent assignment.  If the -f option is supplied, the func-
              tions corresponding to the names are so marked.  The -a option restricts the
              variables  to indexed arrays; the -A option restricts the variables to asso-
              ciative arrays.  If no name arguments are given, or if the -p option is sup-
              plied, a list of all readonly names is printed.  The -p option causes output
              to be displayed in a format that may be reused as input.  If a variable name
              is  followed by =word, the value of the variable is set to word.  The return
              status is 0 unless an invalid option is encountered, one of the names is not
              a  valid  shell  variable  name, or -f is supplied with a name that is not a
              function.

       return [n]
              Causes a function to exit with the return value specified by  n.   If  n  is
              omitted, the return status is that of the last command executed in the func-
              tion body.  If used outside a function, but during execution of a script  by
              the  .   (source) command, it causes the shell to stop executing that script
              and return either n or the exit status of the last command  executed  within
              the script as the exit status of the script.  If used outside a function and
              not during execution of a script by ., the return status is false.  Any com-
              mand  associated  with  the RETURN trap is executed before execution resumes
              after the function or script.

       set [--abefhkmnptuvxBCEHPT] [-o option] [arg ...]
       set [+abefhkmnptuvxBCEHPT] [+o option] [arg ...]
              Without options, the name and value of each shell variable are displayed  in
              a format that can be reused as input for setting or resetting the currently-
              set variables.  Read-only variables cannot be reset.  In  posix  mode,  only
              shell  variables  are listed.  The output is sorted according to the current
              locale.  When options are specified, they set  or  unset  shell  attributes.
              Any  arguments  remaining  after option processing are treated as values for
              the positional parameters and are assigned, in order, to $1,  $2,  ...   $n.
              Options, if specified, have the following meanings:
              -a      Automatically  mark  variables  and  functions which are modified or
                      created for export to the environment of subsequent commands.
              -b      Report the status of terminated background jobs immediately,  rather
                      than  before  the  next primary prompt.  This is effective only when
                      job control is enabled.
              -e      Exit immediately if a pipeline (which may consist of a single simple
                      command),  a subshell command enclosed in parentheses, or one of the
                      commands executed as part of a command list enclosed by braces  (see
                      SHELL  GRAMMAR  above) exits with a non-zero status.  The shell does
                      not exit if the command that fails is part of the command list imme-
                      diately following a while or until keyword, part of the test follow-
                      ing the if or elif reserved words, part of any command executed in a
                      &&  or  || list except the command following the final && or ||, any
                      command in a pipeline but the last, or if the command's return value
                      is being inverted with !.  A trap on ERR, if set, is executed before
                      the shell exits.  This option applies to the shell  environment  and
                      each subshell environment separately (see COMMAND EXECUTION ENVIRON-
                      MENT above), and may cause subshells to exit  before  executing  all
                      the commands in the subshell.
              -f      Disable pathname expansion.
              -h      Remember  the  location of commands as they are looked up for execu-
                      tion.  This is enabled by default.
              -k      All arguments in the form of assignment statements are placed in the
                      environment  for  a command, not just those that precede the command
                      name.
              -m      Monitor mode.  Job control is enabled.  This option is on by default
                      for  interactive  shells on systems that support it (see JOB CONTROL
                      above).  Background processes run in a separate process group and  a
                      line  containing their exit status is printed upon their completion.
              -n      Read commands but do not execute them.  This may be used to check  a
                      shell  script  for  syntax  errors.   This is ignored by interactive
                      shells.
              -o option-name
                      The option-name can be one of the following:
                      allexport
                              Same as -a.
                      braceexpand
                              Same as -B.
                      emacs   Use an emacs-style command line editing interface.  This  is
                              enabled by default when the shell is interactive, unless the
                              shell is started with the  --noediting  option.   This  also
                              affects the editing interface used for read -e.
                      errexit Same as -e.
                      errtrace
                              Same as -E.
                      functrace
                              Same as -T.
                      hashall Same as -h.
                      histexpand
                              Same as -H.
                      history Enable  command  history,  as described above under HISTORY.
                              This option is on by default in interactive shells.
                      ignoreeof
                              The effect is as if the shell command  ''IGNOREEOF=10''  had
                              been executed (see Shell Variables above).
                      keyword Same as -k.
                      monitor Same as -m.
                      noclobber
                              Same as -C.
                      noexec  Same as -n.
                      noglob  Same as -f.
                      nolog   Currently ignored.
                      notify  Same as -b.
                      nounset Same as -u.
                      onecmd  Same as -t.
                      physical
                              Same as -P.
                      pipefail
                              If  set,  the return value of a pipeline is the value of the
                              last (rightmost) command to exit with a non-zero status,  or
                              zero  if  all  commands  in  the pipeline exit successfully.
                              This option is disabled by default.
                      posix   Change the behavior of bash where the default operation dif-
                              fers  from  the  POSIX standard to match the standard (posix
                              mode).
                      privileged
                              Same as -p.
                      verbose Same as -v.
                      vi      Use a vi-style command line editing  interface.   This  also
                              affects the editing interface used for read -e.
                      xtrace  Same as -x.
                      If  -o  is  supplied  with no option-name, the values of the current
                      options are printed.  If +o  is  supplied  with  no  option-name,  a
                      series  of  set  commands to recreate the current option settings is
                      displayed on the standard output.
              -p      Turn on privileged mode.  In this mode, the $ENV and $BASH_ENV files
                      are  not processed, shell functions are not inherited from the envi-
                      ronment, and the SHELLOPTS, BASHOPTS, CDPATH, and  GLOBIGNORE  vari-
                      ables, if they appear in the environment, are ignored.  If the shell
                      is started with the effective user (group) id not equal to the  real
                      user  (group)  id,  and the -p option is not supplied, these actions
                      are taken and the effective user id is set to the real user id.   If
                      the  -p  option is supplied at startup, the effective user id is not
                      reset.  Turning this option off causes the effective user and  group
                      ids to be set to the real user and group ids.
              -t      Exit after reading and executing one command.
              -u      Treat  unset variables and parameters other than the special parame-
                      ters "@" and "*" as an error when  performing  parameter  expansion.
                      If  expansion  is  attempted  on an unset variable or parameter, the
                      shell prints an error message, and, if not interactive, exits with a
                      non-zero status.
              -v      Print shell input lines as they are read.
              -x      After  expanding  each  simple  command,  for command, case command,
                      select command, or arithmetic  for  command,  display  the  expanded
                      value  of PS4, followed by the command and its expanded arguments or
                      associated word list.
              -B      The shell performs brace  expansion  (see  Brace  Expansion  above).
                      This is on by default.
              -C      If set, bash does not overwrite an existing file with the >, >&, and
                      <> redirection operators.  This may be overridden when creating out-
                      put files by using the redirection operator >| instead of >.
              -E      If  set,  any  trap  on ERR is inherited by shell functions, command
                      substitutions, and commands executed in a subshell environment.  The
                      ERR trap is normally not inherited in such cases.
              -H      Enable  !  style history substitution.  This option is on by default
                      when the shell is interactive.
              -P      If set, the shell does not follow symbolic links when executing com-
                      mands such as cd that change the current working directory.  It uses
                      the physical directory structure instead.  By default, bash  follows
                      the  logical  chain  of  directories  when performing commands which
                      change the current directory.
              -T      If set, any traps on DEBUG and RETURN are inherited by  shell  func-
                      tions,  command  substitutions,  and commands executed in a subshell
                      environment.  The DEBUG and RETURN traps are normally not  inherited
                      in such cases.
              --      If  no  arguments follow this option, then the positional parameters
                      are unset.  Otherwise, the positional  parameters  are  set  to  the
                      args, even if some of them begin with a -.
              -       Signal  the  end of options, cause all remaining args to be assigned
                      to the positional parameters.  The -x and -v options are turned off.
                      If there are no args, the positional parameters remain unchanged.

              The  options are off by default unless otherwise noted.  Using + rather than
              - causes these options to be turned off.  The options can also be  specified
              as  arguments to an invocation of the shell.  The current set of options may
              be found in $-.  The return status is always true unless an  invalid  option
              is encountered.

       shift [n]
              The  positional  parameters  from n+1 ... are renamed to $1 ....  Parameters
              represented by the numbers $# down to $#-n+1 are unset.  n must  be  a  non-
              negative  number  less  than  or  equal to $#.  If n is 0, no parameters are
              changed.  If n is not given, it is assumed to be 1.  If n  is  greater  than
              $#, the positional parameters are not changed.  The return status is greater
              than zero if n is greater than $# or less than zero; otherwise 0.

       shopt [-pqsu] [-o] [optname ...]
              Toggle the values of variables controlling optional shell behavior.  With no
              options, or with the -p option, a list of all settable options is displayed,
              with an indication of whether or not each is set.  The -p option causes out-
              put  to  be  displayed in a form that may be reused as input.  Other options
              have the following meanings:
              -s     Enable (set) each optname.
              -u     Disable (unset) each optname.
              -q     Suppresses normal output (quiet mode); the  return  status  indicates
                     whether  the  optname is set or unset.  If multiple optname arguments
                     are given with -q, the return status is  zero  if  all  optnames  are
                     enabled; non-zero otherwise.
              -o     Restricts the values of optname to be those defined for the -o option
                     to the set builtin.

              If either -s or -u is used with no optname arguments, the display is limited
              to  those  options  which  are set or unset, respectively.  Unless otherwise
              noted, the shopt options are disabled (unset) by default.

              The return status when listing options is zero if all optnames are  enabled,
              non-zero otherwise.  When setting or unsetting options, the return status is
              zero unless an optname is not a valid shell option.

              The list of shopt options is:

              autocd  If set, a command name that is the name of a directory  is  executed
                      as  if  it were the argument to the cd command.  This option is only
                      used by interactive shells.
              cdable_vars
                      If set, an argument to the cd builtin command that is not  a  direc-
                      tory  is  assumed  to  be  the name of a variable whose value is the
                      directory to change to.
              cdspell If set, minor errors in the spelling of a directory component  in  a
                      cd command will be corrected.  The errors checked for are transposed
                      characters, a missing character, and one character too many.   If  a
                      correction  is  found,  the  corrected file name is printed, and the
                      command proceeds.  This option is only used by interactive shells.
              checkhash
                      If set, bash checks that a command found in the  hash  table  exists
                      before  trying to execute it.  If a hashed command no longer exists,
                      a normal path search is performed.
              checkjobs
                      If set, bash lists the status of any stopped and running jobs before
                      exiting  an interactive shell.  If any jobs are running, this causes
                      the exit to be deferred until a second exit is attempted without  an
                      intervening command (see JOB CONTROL above).  The shell always post-
                      pones exiting if any jobs are stopped.
              checkwinsize
                      If set, bash checks the window size after each command and, if  nec-
                      essary, updates the values of LINES and COLUMNS.
              cmdhist If  set,  bash attempts to save all lines of a multiple-line command
                      in the same history entry.  This allows easy  re-editing  of  multi-
                      line commands.
              compat31
                      If  set,  bash  changes  its  behavior  to  that of version 3.1 with
                      respect  to  quoted  arguments  to  the  conditional  command's   =~
                      operator.
              compat32
                      If  set,  bash  changes  its  behavior  to  that of version 3.2 with
                      respect to locale-specific string comparison when using  the  condi-
                      tional command's < and > operators.
              compat40
                      If  set,  bash  changes  its  behavior  to  that of version 4.0 with
                      respect to locale-specific string comparison when using  the  condi-
                      tional  command's < and > operators and the effect of interrupting a
                      command list.
              dirspell
                      If set, bash attempts spelling correction on directory names  during
                      word  completion  if  the directory name initially supplied does not
                      exist.
              dotglob If set, bash includes filenames beginning with a '.' in the  results
                      of pathname expansion.
              execfail
                      If  set,  a non-interactive shell will not exit if it cannot execute
                      the file specified as an argument to the exec builtin  command.   An
                      interactive shell does not exit if exec fails.
              expand_aliases
                      If set, aliases are expanded as described above under ALIASES.  This
                      option is enabled by default for interactive shells.
              extdebug
                      If set, behavior intended for use by debuggers is enabled:
                      1.     The -F option to the declare builtin displays the source file
                             name and line number corresponding to each function name sup-
                             plied as an argument.
                      2.     If the command run by  the  DEBUG  trap  returns  a  non-zero
                             value, the next command is skipped and not executed.
                      3.     If  the  command  run by the DEBUG trap returns a value of 2,
                             and the shell is executing in a subroutine (a shell  function
                             or  a  shell  script executed by the . or source builtins), a
                             call to return is simulated.
                      4.     BASH_ARGC and BASH_ARGV are updated  as  described  in  their
                             descriptions above.
                      5.     Function  tracing  is  enabled:   command substitution, shell
                             functions, and subshells invoked with ( command ) inherit the
                             DEBUG and RETURN traps.
                      6.     Error  tracing is enabled:  command substitution, shell func-
                             tions, and subshells invoked with (  command  )  inherit  the
                             ERROR trap.
              extglob If set, the extended pattern matching features described above under
                      Pathname Expansion are enabled.
              extquote
                      If set, $'string' and $"string" quoting is performed within ${param-
                      eter}  expansions enclosed in double quotes.  This option is enabled
                      by default.
              failglob
                      If set, patterns which  fail  to  match  filenames  during  pathname
                      expansion result in an expansion error.
              force_fignore
                      If  set,  the suffixes specified by the FIGNORE shell variable cause
                      words to be ignored when performing  word  completion  even  if  the
                      ignored  words  are  the only possible completions.  See SHELL VARI-
                      ABLES above for a description of FIGNORE.  This option is enabled by
                      default.
              globstar
                      If  set,  the  pattern  ** used in a pathname expansion context will
                      match a files and zero or more directories and  subdirectories.   If
                      the  pattern is followed by a /, only directories and subdirectories
                      match.
              gnu_errfmt
                      If set, shell error messages are written in the standard  GNU  error
                      message format.
              histappend
                      If  set, the history list is appended to the file named by the value
                      of the HISTFILE variable when the shell exits, rather than overwrit-
                      ing the file.
              histreedit
                      If  set, and readline is being used, a user is given the opportunity
                      to re-edit a failed history substitution.
              histverify
                      If set, and readline is being used, the results of history substitu-
                      tion  are  not immediately passed to the shell parser.  Instead, the
                      resulting line is loaded into the readline editing buffer,  allowing
                      further modification.
              hostcomplete
                      If  set,  and  readline  is being used, bash will attempt to perform
                      hostname completion when a word containing a @  is  being  completed
                      (see  Completing under READLINE above).  This is enabled by default.
              huponexit
                      If set, bash will send SIGHUP to all jobs when an interactive  login
                      shell exits.
              interactive_comments
                      If  set,  allow  a  word beginning with # to cause that word and all
                      remaining characters on that line to be ignored  in  an  interactive
                      shell (see COMMENTS above).  This option is enabled by default.
              lithist If  set,  and the cmdhist option is enabled, multi-line commands are
                      saved to the history with embedded newlines rather than using  semi-
                      colon separators where possible.
              login_shell
                      The  shell  sets  this option if it is started as a login shell (see
                      INVOCATION above).  The value may not be changed.
              mailwarn
                      If set, and a file that bash is checking for mail has been  accessed
                      since  the last time it was checked, the message ''The mail in mail-
                      file has been read'' is displayed.
              no_empty_cmd_completion
                      If set, and readline is being used, bash will not attempt to  search
                      the PATH for possible completions when completion is attempted on an
                      empty line.
              nocaseglob
                      If set, bash matches filenames in a  case-insensitive  fashion  when
                      performing pathname expansion (see Pathname Expansion above).
              nocasematch
                      If  set,  bash  matches  patterns in a case-insensitive fashion when
                      performing matching while executing case or [[ conditional commands.
              nullglob
                      If  set,  bash  allows  patterns  which match no files (see Pathname
                      Expansion above) to expand to a null string, rather than themselves.
              progcomp
                      If  set,  the  programmable  completion facilities (see Programmable
                      Completion above) are enabled.  This option is enabled by default.
              promptvars
                      If set, prompt strings undergo parameter expansion, command  substi-
                      tution, arithmetic expansion, and quote removal after being expanded
                      as described in PROMPTING above.  This option is enabled by default.
              restricted_shell
                      The  shell sets this option if it is started in restricted mode (see
                      RESTRICTED SHELL below).  The value may not be changed.  This is not
                      reset  when  the  startup  files  are executed, allowing the startup
                      files to discover whether or not a shell is restricted.
              shift_verbose
                      If set, the shift builtin prints an error  message  when  the  shift
                      count exceeds the number of positional parameters.
              sourcepath
                      If  set,  the  source (.) builtin uses the value of PATH to find the
                      directory containing the file supplied as an argument.  This  option
                      is enabled by default.
              xpg_echo
                      If  set,  the  echo  builtin  expands  backslash-escape sequences by
                      default.
       suspend [-f]
              Suspend the execution of this shell until it receives a SIGCONT signal. When
              the  suspended  shell is a background process, it can be restarted by the fg
              command. For more information, read the JOB  CONTROL  section.  The  suspend
              command  can  not suspend the login shell. However, when -f option is speci-
              fied, suspend command can suspend even login shell.  The return status is  0
              unless  the shell is a login shell and -f is not supplied, or if job control
              is not enabled.
       test expr
       [ expr ]
              Return a status of 0 or 1 depending on the  evaluation  of  the  conditional
              expression  expr.   Each  operator  and operand must be a separate argument.
              Expressions are composed of the primaries described above under  CONDITIONAL
              EXPRESSIONS.   test  does  not  accept  any  options, nor does it accept and
              ignore an argument of -- as signifying the end of options.

              Expressions may  be  combined  using  the  following  operators,  listed  in
              decreasing  order  of  precedence.   The evaluation depends on the number of
              arguments; see below.
              ! expr True if expr is false.
              ( expr )
                     Returns the value of expr.  This may be used to override  the  normal
                     precedence of operators.
              expr1 -a expr2
                     True if both expr1 and expr2 are true.
              expr1 -o expr2
                     True if either expr1 or expr2 is true.

              test  and  [  evaluate conditional expressions using a set of rules based on
              the number of arguments.

              0 arguments
                     The expression is false.
              1 argument
                     The expression is true if and only if the argument is not null.
              2 arguments
                     If the first argument is !, the expression is true if and only if the
                     second  argument  is null.  If the first argument is one of the unary
                     conditional operators listed above under CONDITIONAL EXPRESSIONS, the
                     expression  is true if the unary test is true.  If the first argument
                     is not a valid unary conditional operator, the expression is false.
              3 arguments
                     If the second argument is one of  the  binary  conditional  operators
                     listed above under CONDITIONAL EXPRESSIONS, the result of the expres-
                     sion is the result of the binary test using the first and third argu-
                     ments  as  operands.   The  -a and -o operators are considered binary
                     operators when there are three arguments.  If the first  argument  is
                     !,  the value is the negation of the two-argument test using the sec-
                     ond and third arguments.  If the first argument is exactly ( and  the
                     third  argument  is exactly ), the result is the one-argument test of
                     the second argument.  Otherwise, the expression is false.
              4 arguments
                     If the first argument is !, the result is the negation of the  three-
                     argument  expression composed of the remaining arguments.  Otherwise,
                     the expression is parsed and evaluated according to precedence  using
                     the rules listed above.
              5 or more arguments
                     The  expression is parsed and evaluated according to precedence using
                     the rules listed above.

       times  Print the accumulated user and system times for the shell and for  processes
              run from the shell.  The return status is 0.

       trap [-lp] [[arg] sigspec ...]
              The command arg is to be read and executed when the shell receives signal(s)
              sigspec.  If arg is absent (and there is a single sigspec) or -, each speci-
              fied  signal  is  reset  to  its original disposition (the value it had upon
              entrance to the shell).  If arg is the null string the signal  specified  by
              each sigspec is ignored by the shell and by the commands it invokes.  If arg
              is not present and -p has been supplied, then the trap  commands  associated
              with each sigspec are displayed.  If no arguments are supplied or if only -p
              is given, trap prints the list of commands associated with each signal.  The
              -l  option causes the shell to print a list of signal names and their corre-
              sponding numbers.  Each sigspec is either a signal  name  defined  in  <sig-
              nal.h>,  or  a signal number.  Signal names are case insensitive and the SIG
              prefix is optional.

              If a sigspec is EXIT (0) the command arg is executed on exit from the shell.
              If  a sigspec is DEBUG, the command arg is executed before every simple com-
              mand, for command, case command, select command, every arithmetic  for  com-
              mand,  and  before the first command executes in a shell function (see SHELL
              GRAMMAR above).  Refer to the description of  the  extdebug  option  to  the
              shopt  builtin for details of its effect on the DEBUG trap.  If a sigspec is
              RETURN, the command arg is executed each time a shell function or  a  script
              executed with the . or source builtins finishes executing.

              If  a  sigspec is ERR, the command arg is executed whenever a simple command
              has a non-zero exit status, subject to the following  conditions.   The  ERR
              trap is not executed if the failed command is part of the command list imme-
              diately following a while or until keyword, part of the test in an if state-
              ment,  part  of  a  command executed in a && or || list, or if the command's
              return value is being inverted via !.  These are the same conditions  obeyed
              by the errexit option.

              Signals  ignored upon entry to the shell cannot be trapped, reset or listed.
              Trapped signals that are not being ignored are reset to their original  val-
              ues  in  a subshell or subshell environment when one is created.  The return
              status is false if any sigspec is invalid; otherwise trap returns true.

       type [-aftpP] name [name ...]
              With no options, indicate how each name would be interpreted if  used  as  a
              command  name.   If the -t option is used, type prints a string which is one
              of alias, keyword, function, builtin, or file if name  is  an  alias,  shell
              reserved  word,  function, builtin, or disk file, respectively.  If the name
              is not found, then nothing is printed,  and  an  exit  status  of  false  is
              returned.   If  the  -p  option is used, type either returns the name of the
              disk file that would be executed if name were specified as a  command  name,
              or  nothing if ''type -t name'' would not return file.  The -P option forces
              a PATH search for each name, even if ''type -t name'' would not return file.
              If  a  command  is hashed, -p and -P print the hashed value, not necessarily
              the file that appears first in PATH.  If the -a option is used, type  prints
              all  of  the  places  that  contain an executable named name.  This includes
              aliases and functions, if and only if the -p option is not also  used.   The
              table of hashed commands is not consulted when using -a.  The -f option sup-
              presses shell function lookup, as with the command  builtin.   type  returns
              true if all of the arguments are found, false if any are not found.

       ulimit [-HSTabcdefilmnpqrstuvx [limit]]
              Provides  control over the resources available to the shell and to processes
              started by it, on systems that allow such control.  The -H  and  -S  options
              specify  that  the hard or soft limit is set for the given resource.  A hard
              limit cannot be increased by a non-root user once it is set;  a  soft  limit
              may be increased up to the value of the hard limit.  If neither -H nor -S is
              specified, both the soft and hard limits are set.  The value of limit can be
              a number in the unit specified for the resource or one of the special values
              hard, soft, or unlimited, which stand for the current hard limit,  the  cur-
              rent  soft limit, and no limit, respectively.  If limit is omitted, the cur-
              rent value of the soft limit of the  resource  is  printed,  unless  the  -H
              option  is  given.  When more than one resource is specified, the limit name
              and unit are printed before the value.  Other  options  are  interpreted  as
              follows:
              -a     All current limits are reported
              -b     The maximum socket buffer size
              -c     The maximum size of core files created
              -d     The maximum size of a process's data segment
              -e     The maximum scheduling priority ("nice")
              -f     The maximum size of files written by the shell and its children
              -i     The maximum number of pending signals
              -l     The maximum size that may be locked into memory
              -m     The maximum resident set size (many systems do not honor this limit)
              -n     The  maximum  number  of  open  file descriptors (most systems do not
                     allow this value to be set)
              -p     The pipe size in 512-byte blocks (this may not be set)
              -q     The maximum number of bytes in POSIX message queues
              -r     The maximum real-time scheduling priority
              -s     The maximum stack size
              -t     The maximum amount of cpu time in seconds
              -u     The maximum number of processes available to a single user
              -v     The maximum amount of virtual memory available to the shell
              -x     The maximum number of file locks
              -T     The maximum number of threads

              If limit is given, it is the new value of the  specified  resource  (the  -a
              option is display only).  If no option is given, then -f is assumed.  Values
              are in 1024-byte increments, except for -t, which is in seconds,  -p,  which
              is  in  units of 512-byte blocks, and -T, -b, -n, and -u, which are unscaled
              values.  The return status is 0 unless an invalid option or argument is sup-
              plied, or an error occurs while setting a new limit.

       umask [-p] [-S] [mode]
              The user file-creation mask is set to mode.  If mode begins with a digit, it
              is interpreted as an octal number; otherwise it is interpreted as a symbolic
              mode  mask  similar  to  that accepted by chmod(1).  If mode is omitted, the
              current value of the mask is printed.  The -S option causes the mask  to  be
              printed  in symbolic form; the default output is an octal number.  If the -p
              option is supplied, and mode is omitted, the output is in a form that may be
              reused  as  input.   The  return  status  is  0 if the mode was successfully
              changed or if no mode argument was supplied, and false otherwise.

       unalias [-a] [name ...]
              Remove each name from the list of defined aliases.  If -a is  supplied,  all
              alias  definitions  are removed.  The return value is true unless a supplied
              name is not a defined alias.

       unset [-fv] [name ...]
              For each name, remove the corresponding variable or function.  If no options
              are  supplied,  or the -v option is given, each name refers to a shell vari-
              able.  Read-only variables may not be unset.  If -f is specified, each  name
              refers  to  a  shell function, and the function definition is removed.  Each
              unset variable or function is removed from the environment passed to  subse-
              quent  commands.   If  any  of  COMP_WORDBREAKS,  RANDOM,  SECONDS,  LINENO,
              HISTCMD, FUNCNAME, GROUPS, or DIRSTACK are unset, they  lose  their  special
              properties,  even  if  they are subsequently reset.  The exit status is true
              unless a name is readonly.

       wait [n ...]
              Wait for each specified process and return its termination status.   Each  n
              may be a process ID or a job specification; if a job spec is given, all pro-
              cesses in that job's pipeline are waited for.  If n is not given,  all  cur-
              rently active child processes are waited for, and the return status is zero.
              If n specifies a non-existent process or job,  the  return  status  is  127.
              Otherwise,  the  return status is the exit status of the last process or job
              waited for.

SEE ALSO
       bash(1), sh(1)



GNU Bash-4.0                      2004 Apr 20                 BASH_BUILTINS(1)

Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2017-08-21 23:33 @127.0.0.1 CrawledBy CCBot/2.0 (http://commoncrawl.org/faq/)
Valid XHTML 1.0!Valid CSS!