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VISUDO


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BSD mandoc

Sudo 1.8.6p3

 

NAME

visudo

– edit the sudoers file

 

SYNOPSIS

visudo

[-chqsV

]

-words

[-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 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


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 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


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


 

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



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