visudo(8)

NAME
visudo - edit the sudoers file

SYNOPSIS
visudo [ -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 message to try again later. In the default configuration, the vi(1) editor is used, but there is a compile time option to allow use of whatever editor the environment variables EDITOR or VISUAL are set to.

visudo parses the sudoers file after the edit and will not save the changes if there is a syntax error. Upon finding an error, a message will be printed stating the line number(s) that the error occurred on and the user will receive the "What now?" prompt. At this point the user may enter "e" to re-edit the sudoers file, enter "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 execute sudo again until the error is fixed. Any other command at this prompt will print a short help message. When editing 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 option: 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 upper case letters, digits, and the underscore ('_') character. The -V (version) option causes visudo to print the version number and exit.

ERRORS
Someone else is currently editing the sudoers file. You didn't run visudo as root. Your userid does not appear in the system passwd file. 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 upper case 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                 Used by visudo as the editor to use
 VISUAL                 Used by 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            <Todd.Miller@courtesan.com>
See the HISTORY file in the sudo distribution for more details.

BUGS
If you feel you have found a bug in sudo, please submit a bug report at http://www.courtesan.com/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
sudo(8), vipw(8).