path: root/usr.bin/sudo/visudo.8

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.IX Title "visudo 8"
.TH visudo 8 "1.6.6" "April 25, 2002" "MAINTENANCE COMMANDS"
.UC
.SH "NAME"
visudo \- edit the sudoers file
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
\&\fBvisudo\fR [ \fB\-c\fR ] [ \fB\-f\fR \fIsudoers\fR ] [ \fB\-q\fR ] [ \fB\-s\fR ] [ \fB\-V\fR ]
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBvisudo\fR edits the \fIsudoers\fR file in a safe fashion, analogous to
\&\fIvipw\fR\|(8).  \fBvisudo\fR locks the \fIsudoers\fR file against multiple
simultaneous edits, provides basic sanity checks, and checks
for parse errors.  If the \fIsudoers\fR file is currently being
edited you will receive a message to try again later.
.PP
There is a hard-coded list of editors that \fBvisudo\fR will use set
at compile-time that may be overridden via the \fIeditor\fR \fIsudoers\fR
\&\f(CW\*(C`Default\*(C'\fR variable.  This list defaults to the path to \fIvi\fR\|(1) on
your system, as determined by the \fIconfigure\fR script.  Normally,
\&\fBvisudo\fR does not honor the \f(CW\*(C`EDITOR\*(C'\fR or \f(CW\*(C`VISUAL\*(C'\fR environment
variables unless they contain an editor in the aforementioned editors
list.  However, if \fBvisudo\fR is configured with the \fI\*(--with-enveditor\fR
flag or the \fIenveditor\fR \f(CW\*(C`Default\*(C'\fR variable is set in \fIsudoers\fR,
\&\fBvisudo\fR will use any the editor defines by \f(CW\*(C`EDITOR\*(C'\fR or \f(CW\*(C`VISUAL\*(C'\fR.
Note that this can be a security hole since it allows the user to
execute any program they wish simply by setting \f(CW\*(C`EDITOR\*(C'\fR or \f(CW\*(C`VISUAL\*(C'\fR.
.PP
\&\fBvisudo\fR parses the \fIsudoers\fR file after the edit and will
not save the changes if there is a syntax error.  Upon finding
an error, \fBvisudo\fR will print a message stating the line \fInumber\fR\|(s)
where the error occurred and the user will receive the
\&\*(L"What now?\*(R" prompt.  At this point the user may enter \*(L"e\*(R"
to re-edit the \fIsudoers\fR file, \*(L"x\*(R" to exit without
saving the changes, or \*(L"Q\*(R" to quit and save changes.  The
\&\*(L"Q\*(R" option should be used with extreme care because if \fBvisudo\fR
believes there to be a parse error, so will \fBsudo\fR and no one
will be able to \fBsudo\fR again until the error is fixed.
If \*(L"e\*(R" is typed to edit the  \fIsudoers\fR 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).
.SH "OPTIONS"
.IX Header "OPTIONS"
\&\fBvisudo\fR accepts the following command line options:
.Ip "\-c" 4
.IX Item "-c"
Enable \fBcheck-only\fR mode.  The existing \fIsudoers\fR file will be
checked for syntax and a message will be printed to the
standard output detailing the status of \fIsudoers\fR.
If the syntax check completes successfully, \fBvisudo\fR will
exit with a value of 0.  If a syntax error is encountered,
\&\fBvisudo\fR will exit with a value of 1.
.Ip "\-f" 4
.IX Item "-f"
Specify and alternate \fIsudoers\fR file location.  With this option
\&\fBvisudo\fR will edit (or check) the \fIsudoers\fR file of your choice,
instead of the default, \f(CW@sysconfdir\fR@/sudoers.  The lock file used
is the specified \fIsudoers\fR file with \*(L".tmp\*(R" appended to it.
.Ip "\-q" 4
.IX Item "-q"
Enable \fBquiet\fR mode.  In this mode details about syntax errors
are not printed.  This option is only useful when combined with
the \fB\-c\fR flag.
.Ip "\-s" 4
.IX Item "-s"
Enable \fBstrict\fR checking of the \fIsudoers\fR file.  If an alias is
used before it is defined, \fBvisudo\fR will consider this a parse
error.  Note that it is not possible to differentiate between an
alias and a hostname or username that consists solely of uppercase
letters, digits, and the underscore ('_') character.
.Ip "\-V" 4
.IX Item "-V"
The \fB\-V\fR (version) option causes \fBvisudo\fR to print its version number
and exit.
.SH "ERRORS"
.IX Header "ERRORS"
.Ip "sudoers file busy, try again later." 4
.IX Item "sudoers file busy, try again later."
Someone else is currently editing the \fIsudoers\fR file.
.Ip "/etc/sudoers.tmp: Permission denied" 4
.IX Item "/etc/sudoers.tmp: Permission denied"
You didn't run \fBvisudo\fR as root.
.Ip "Can't find you in the passwd database" 4
.IX Item "Can't find you in the passwd database"
Your userid does not appear in the system passwd file.
.Ip "Warning: undeclared Alias referenced near ..." 4
.IX Item "Warning: undeclared Alias referenced near ..."
Either you are using a {User,Runas,Host,Cmnd}_Alias before
defining it or you have a user or hostname listed that
consists solely of uppercase letters, digits, and the
underscore ('_') character.  If the latter, you can ignore
the warnings (\fBsudo\fR will not complain).  In \fB\-s\fR (strict)
mode these are errors, not warnings.
.SH "ENVIRONMENT"
.IX Header "ENVIRONMENT"
The following environment variables are used only if \fBvisudo\fR
was configured with the \fI\*(--with-env-editor\fR option:
.PP
.Vb 2
\& EDITOR                 Invoked by visudo as the editor to use
\& VISUAL                 Used Invoked visudo if EDITOR is not set
.Ve
.SH "FILES"
.IX Header "FILES"
.Vb 2
\& /etc/sudoers           List of who can run what
\& /etc/sudoers.tmp       Lock file for visudo
.Ve
.SH "AUTHOR"
.IX Header "AUTHOR"
Many people have worked on \fIsudo\fR over the years; this version of
\&\fBvisudo\fR was written by:
.PP
.Vb 1
\& Todd Miller            <Todd.Miller@courtesan.com>
.Ve
See the \s-1HISTORY\s0 file in the sudo distribution or visit
http://www.sudo.ws/sudo/history.html for more details.
.SH "BUGS"
.IX Header "BUGS"
If you feel you have found a bug in sudo, please submit a bug report
at http://www.sudo.ws/sudo/bugs/
.SH "DISCLAIMER"
.IX Header "DISCLAIMER"
\&\fBVisudo\fR is provided ``\s-1AS\s0 \s-1IS\s0'' 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 \s-1LICENSE\s0 file distributed with \fBsudo\fR for complete details.
.SH "CAVEATS"
.IX Header "CAVEATS"
There is no easy way to prevent a user from gaining a root shell if 
the editor used by \fBvisudo\fR allows shell escapes.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fIvi\fR\|(1), \fIsudo\fR\|(8), \fIvipw\fR\|(8).