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 multiple simultaneous edits, provides basic sanity checks, and checks
for parse errors. If the sudoers file is currently being edited you will receive a mes-
sage 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 num-
ber(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, @sysconfdir@/sudoers.
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 differenti-
ate between an alias and a hostname or username that consists solely of uppercase let-
ters, 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, digits, 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.
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 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.
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)
1.6.7 March 13, 2003 VISUDO(8)
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