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mesg.1
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.\" Copyright (c) 1987, 1990, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" @(#)mesg.1 8.1 (Berkeley) 6/6/93
.\"
.TH MESG 1 "July 2014" "util-linux" "User Commands"
.SH NAME
mesg \- display (or do not display) messages from other users
.SH SYNOPSIS
.B mesg
[option]
.RB [ n | y ]
.SH DESCRIPTION
The
.B mesg
utility is invoked by a user to control write access others have to the
terminal device associated with standard error output. If write access
is allowed, then programs such as
.BR talk (1)
and
.BR write (1)
may display messages on the terminal.
.PP
Traditionally, write access is allowed by default. However, as users
become more conscious of various security risks, there is a trend to remove
write access by default, at least for the primary login shell. To make
sure your ttys are set the way you want them to be set,
.B mesg
should be executed in your login scripts.
.PP
The
.B mesg
utility silently exits with error status 2 if not executed on terminal. In this
case execute
.B mesg
is pointless. The command line option \fB\-\-verbose\fR forces
mesg to print a warning in this situation. This behaviour has been introduced
in version 2.33.
.SH ARGUMENTS
.TP
.B n
Disallow messages.
.TP
.B y
Allow messages to be displayed.
.PP
If no arguments are given,
.B mesg
shows the current message status on standard error output.
.SH OPTIONS
.TP
.BR \-v , " \-\-verbose"
Explain what is being done.
.TP
.BR \-V , " \-\-version"
Display version information and exit.
.TP
.BR \-h , " \-\-help"
Display help text and exit.
.SH EXIT STATUS
The
.B mesg
utility exits with one of the following values:
.RS 4
.TP
.B "\ 0"
Messages are allowed.
.TP
.B "\ 1"
Messages are not allowed.
.TP
.B ">1"
An error has occurred.
.RE
.SH FILES
.I /dev/[pt]ty[pq]?
.SH "SEE ALSO"
.BR login (1),
.BR talk (1),
.BR write (1),
.BR wall (1),
.BR xterm (1)
.SH HISTORY
A
.B mesg
command appeared in Version 6 AT&T UNIX.
.SH AVAILABILITY
The mesg command is part of the util-linux package and is available from
https://www.kernel.org/pub/linux/utils/util-linux/.