


VISUDO(8)              MAINTENANCE COMMANDS             VISUDO(8)


NAME
       visudo - edit the sudoers file

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

DESCRIPTION
       visudo edits the sudoers file in a safe fashion, analogous
       to vipw(8).  visudo locks the sudoers file against multi-
       ple 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 EDITOR or
       VISUAL environment variables unless they contain an editor
       in the aforementioned editors list.  However, if visudo is
       configured with the --with-enveditor flag or the enveditor
       Default variable is set in sudoers, visudo will use any
       the editor defines by EDITOR or VISUAL.  Note that this
       can be a security hole since it allows the user to execute
       any program they wish simply by setting EDITOR or VISUAL.

       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 stating 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



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VISUDO(8)              MAINTENANCE COMMANDS             VISUDO(8)


           file of your choice, instead of the default,
           @sysconfdir@/sudoers.  The lock file used is the spec-
           ified 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 con-
           sider this a parse error.  Note that it is not possi-
           ble 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.

ERRORS
       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 lat-
           ter, you can ignore the warnings (sudo will not com-
           plain).  In -s (strict) mode these are errors, not
           warnings.

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

        EDITOR                 Invoked by visudo as the editor to use
        VISUAL                 Used Invoked visudo if EDITOR is not set

FILES
        /etc/sudoers           List of who can run what
        /etc/sudoers.tmp       Lock file for visudo

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

        Todd Miller            <Todd.Miller@courtesan.com>




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VISUDO(8)              MAINTENANCE COMMANDS             VISUDO(8)


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

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

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 particular
       purpose are disclaimed.  See the LICENSE file distributed
       with sudo for complete 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.

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





































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