VISUDO(8) BSD System Manager's Manual VISUDO(8)
NAME
visudo — edit the sudoers file
SYNOPSIS
visudo [-chqsV] [-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 one or more editors that visudo will use set at compile-time that may be overrid‐
den via the editor sudoers Default variable. This list defaults to /usr/local/bin/vi. Normally, visudo does
not honor the VISUAL or EDITOR environment variables unless they contain an editor in the aforementioned editors
list. However, if visudo is configured with the --with-env-editor option 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 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).
The options are as follows:
-c Enable check-only mode. The existing sudoers file will be checked for syntax errors, owner and
mode. A message will be printed to the standard output describing the status of sudoers unless the
-q option was specified. If the check completes successfully, visudo will exit with a value of 0.
If an error is encountered, visudo will exit with a value of 1.
-f sudoers 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/sudoers. The lock file used is the speci‐
fied sudoers file with “.tmp” appended to it. In check-only mode only, the argument to -f may be
‘-’, indicating that sudoers will be read from the standard input.
-h The -h (help) option causes visudo to print a short help message to the standard output and exit.
-q Enable quiet mode. In this mode details about syntax errors are not printed. This option is only
useful when combined with the -c option.
-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
host name or user name 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 may be consulted depending on the value of the editor and env_editor sudoers
settings:
VISUAL Invoked by visudo as the editor to use
EDITOR Used by visudo if VISUAL is not set
Can't find you in the passwd database
Your user ID does not appear in the system passwd file.
Warning: {User,Runas,Host,Cmnd}_Alias referenced but not defined
Either you are trying to use an undeclared {User,Runas,Host,Cmnd}_Alias or you have a user or host name
listed that consists solely of uppercase letters, digits, and the underscore (‘_’) character. In the lat‐
ter case, you can ignore the warnings (sudo will not complain). In -s (strict) mode these are errors, not
warnings.
Warning: unused {User,Runas,Host,Cmnd}_Alias
The specified {User,Runas,Host,Cmnd}_Alias was defined but never used. You may wish to comment out or
remove the unused alias. In -s (strict) mode this is an error, not a warning.
Warning: cycle in {User,Runas,Host,Cmnd}_Alias
The specified {User,Runas,Host,Cmnd}_Alias includes a reference to itself, either directly or through an
alias it includes. This is only a warning by default as sudo will ignore cycles when parsing the sudoers
file.
SEE ALSO
vi(1), sudoers(5), sudo(8), vipw(8)
AUTHORS
Many people have worked on sudo over the years; this version consists of code written primarily by:
Todd C. Miller
See the CONTRIBUTORS file in the sudo distribution (http://www.sudo.ws/sudo/contributors.html) for an exhaustive
list of people who have contributed to sudo.
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 particular purpose are disclaimed. See the LICENSE file dis‐
tributed with sudo or http://www.sudo.ws/sudo/license.html for complete details.
Sudo 1.8.6p7 July 12, 2012 Sudo 1.8.6p7
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