VISUDO(8) MAINTENANCE COMMANDS VISUDO(8)NAMEvisudo - edit the sudoers file
SYNOPSISvisudo [-c] [-q] [-s] [-V] [-f sudoers]
DESCRIPTIONvisudo 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 overridden via the editor sudoers
Default variable. This list defaults to "/usr/bin/editor". 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).
OPTIONSvisudo 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 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 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 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 variables:
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 visudoDIAGNOSTICS
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: {User,Runas,Host,Cmnd}_Alias referenced but not defined
Either you are trying to use an undeclare
{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 latter 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.
SEE ALSOvi(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/history.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.
DISCLAIMERvisudo 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 or
http://www.sudo.ws/sudo/license.html for complete details.
1.7.4 July 14, 2010 VISUDO(8)
