visudo - phpMan

VISUDO(8)                    MAINTENANCE COMMANDS                    VISUDO(8)


NAME
       visudo - edit the sudoers file

SYNOPSIS
       visudo [-c] [-q] [-s] [-V] [-f sudoers]

DESCRIPTION
       visudo edits the sudoers file in a safe fashion, analogous to vipw(8).  visudo
       locks the sudoers file against multiple simultaneous edits, provides basic sanity
       checks, and checks for parse errors.  If the sudoers file is currently being edited
       you will receive a message to try again later.

       There is a hard-coded list of editors that visudo will use set at compile-time that
       may be overridden via the editor sudoers Default variable.  This list defaults to
       the path to vi(1) on your system, as determined by the configure script.  Normally,
       visudo does not honor the VISUAL or EDITOR environment variables unless they con-
       tain an editor in the aforementioned editors list.  However, if visudo is config-
       ured with the --with-enveditor flag or the env_editor Default variable is set in
       sudoers, visudo will use any the editor defines by VISUAL or EDITOR.  Note that
       this can be a security hole since it allows the user to execute any program they
       wish simply by setting VISUAL or EDITOR.

       visudo parses the sudoers file after the edit and will not save the changes if
       there is a syntax error.  Upon finding an error, visudo will print a message stat-
       ing the line number(s) where the error occurred and the user will receive the "What
       now?" prompt.  At this point the user may enter "e" to re-edit the sudoers file,
       "x" to exit without saving the changes, or "Q" to quit and save changes.  The "Q"
       option should be used with extreme care because if visudo believes there to be a
       parse error, so will sudo and no one will be able to sudo again until the error is
       fixed.  If "e" is typed to edit the  sudoers file after a parse error has been
       detected, the cursor will be placed on the line where the error occurred (if the
       editor supports this feature).

OPTIONS
       visudo accepts the following command line options:

       -c  Enable check-only mode.  The existing sudoers file will be checked for syntax
           and a message will be printed to the standard output detailing the status of
           sudoers.  If the syntax check completes successfully, visudo will exit with a
           value of 0.  If a syntax error is encountered, visudo will exit with a value of
           1.

       -f  Specify and alternate sudoers file location.  With this option visudo will edit
           (or check) the sudoers file of your choice, instead of the default, /etc/sudo-
           ers.  The lock file used is the specified sudoers file with ".tmp" appended to
           it.

       -q  Enable quiet mode.  In this mode details about syntax errors are not printed.
           This option is only useful when combined with the -c flag.

       -s  Enable strict checking of the sudoers file.  If an alias is used before it is
           defined, visudo will consider this a parse error.  Note that it is not possible
           to differentiate between an alias and a hostname or username that consists
           solely of uppercase letters, digits, and the underscore ('_') character.

       -V  The -V (version) option causes visudo to print its version number and exit.

ENVIRONMENT
       The following environment variables are used only if visudo was configured with the
       --with-env-editor option:

       VISUAL          Invoked by visudo as the editor to use

       EDITOR          Used by visudo if VISUAL is not set

FILES
       /etc/sudoers            List of who can run what

       /etc/sudoers.tmp        Lock file for visudo

DIAGNOSTICS
       sudoers file busy, try again later.
           Someone else is currently editing the sudoers file.

       /etc/sudoers.tmp: Permission denied
           You didn't run visudo as root.

       Can't find you in the passwd database
           Your userid does not appear in the system passwd file.

       Warning: undeclared Alias referenced near ...
           Either you are using a {User,Runas,Host,Cmnd}_Alias before defining it or you
           have a user or hostname listed that consists solely of uppercase letters, dig-
           its, and the underscore ('_') character.  If the latter, you can ignore the
           warnings (sudo will not complain).  In -s (strict) mode these are errors, not
           warnings.

       Warning: runas_default set after old value is in use ...
           You have a runas_default Defaults setting listed in the sudoers file after its
           value has already been used.  This means that entries prior to the
           runas_default setting will match based on the default value of runas_default
           (root) whereas entries after the runas_default setting will match based on the
           new value.  This is usually unintentional and in most cases the <runas_default>
           setting should be placed before any Runas_Alias or User specifications.  In -s
           (strict) mode this is an error, not a warning.

SEE ALSO
       vi(1), sudoers(5), sudo(8), vipw(8)

AUTHOR
       Many people have worked on sudo over the years; this version of visudo was written
       by:

        Todd Miller

       See the HISTORY file in the sudo distribution or visit http://www.sudo.ws/sudo/his-
       tory.html for more details.

CAVEATS
       There is no easy way to prevent a user from gaining a root shell if the editor used
       by visudo allows shell escapes.

BUGS
       If you feel you have found a bug in visudo, please submit a bug report at
       http://www.sudo.ws/sudo/bugs/

SUPPORT
       Limited free support is available via the sudo-users mailing list, see
       http://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the archives.

DISCLAIMER
       visudo is provided ''AS IS'' and any express or implied warranties, including, but
       not limited to, the implied warranties of merchantability and fitness for a partic-
       ular purpose are disclaimed.  See the LICENSE file distributed with sudo or
       http://www.sudo.ws/sudo/license.html for complete details.


1.6.9p17                         Jun 21, 2008                        VISUDO(8)