VISUDO
Section: Maintenance Commands (8)
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BSD mandoc
Sudo 1.8.10p3
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:
- 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 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
Po sudo
will not complain
Pc .
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 distributed with
sudo
or
http://www.sudo.ws/sudo/license.html for complete details.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- ENVIRONMENT
-
- FILES
-
- DIAGNOSTICS
-
- SEE ALSO
-
- AUTHORS
-
- CAVEATS
-
- BUGS
-
- SUPPORT
-
- DISCLAIMER
-