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VISUDO(8) | System Manager's Manual | VISUDO(8) |
NAME¶
visudo
—
edit the sudoers file
SYNOPSIS¶
visudo |
[-chqsV -f
sudoers-x
file |
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 overridden 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
,--check
- 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,--file
=sudoers- Specify an 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. In check-only mode only, the argument to-f
may be ‘-
’, indicating that sudoers will be read from the standard input. -h
,--help
- Display a short help message to the standard output and exit.
-q
,--quiet
- 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
,--strict
- 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
,--version
- Print the
visudo
and sudoers grammar versions and exit. -x
file,--export
=file- Export sudoers in JSON format and write it to
file. If
file is
‘
-
’, the exported sudoers policy will be written to the standard output. The exported format is intended to be easier for third-party applications to parse than the traditional sudoers format. The various values have explicit types which removes much of the ambiguity of the sudoers format.
ENVIRONMENT¶
The following environment variables may be consulted depending on the value of the editor and env_editor sudoers settings:FILES¶
- /etc/sudoers
- List of who can run what
- /etc/sudoers.tmp
- Lock file for visudo
DIAGNOSTICS¶
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 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 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. 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 onsudo
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 byvisudo
allows shell escapes.
BUGS¶
If you feel you have found a bug invisudo
,
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 distributed with
sudo
or
http://www.sudo.ws/sudo/license.html for complete details.February 15, 2014 | Sudo 1.8.10p3 |