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'\" t
.\" Title: mesg
.\" Author: [see the "AUTHOR(S)" section]
.\" Generator: Asciidoctor 2.0.20
.\" Date: 2025-12-15
.\" Manual: User Commands
.\" Source: util-linux 2.41.3
.\" Language: English
.\"
.TH "MESG" "1" "2025-12-15" "util\-linux 2.41.3" "User Commands"
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.SH "NAME"
mesg \- display (or do not display) messages from other users
.SH "SYNOPSIS"
.sp
\fBmesg\fP [\fIoption\fP] [\fBn\fP|\fBy\fP]
.SH "DESCRIPTION"
.sp
The \fBmesg\fP 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 \fBtalk\fP(1) and \fBwrite\fP(1) may display messages on the terminal.
.sp
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.
.sp
The initial permissions for the terminal are set by \fBlogin\fP(1) according to TTYPERM
and TTYGROUP from /etc/login.defs. The default is mode \fI0620\fP if a tty group is used,
and \fI0600\fP without the group. The default tty group name is "tty".
.sp
To ensure that your ttys are set in a portable and independent manner from system
settings, \fBmesg\fP should be executed in your login scripts.
.sp
\fBmesg\fP modifies the write permissions for a group on the current terminal
device. Since version 2.41, \fBmesg\fP can no longer be compiled to make the
terminal writable for \fIothers\fP and strictly modifies only \fIgroup\fP permissions.
The usual setup is to use a "tty" group and add relevant users to this group.
Alternatively, a less secure solution is to set utilities like \fBwrite\fP(1) or
\fBwall\fP(1) to setgid for the "tty" group.
.sp
The \fBmesg\fP utility silently exits with error status 2 if not executed on a terminal. In this case executing \fBmesg\fP is pointless. The command line option \fB\-\-verbose\fP forces \fBmesg\fP to print a warning in this situation. This behaviour has been introduced in version 2.33.
.SH "ARGUMENTS"
.sp
\fBn\fP
.RS 4
Disallow messages.
.RE
.sp
\fBy\fP
.RS 4
Allow messages to be displayed.
.RE
.sp
If no arguments are given, \fBmesg\fP shows the current message status on standard error output.
.SH "OPTIONS"
.sp
\fB\-v\fP, \fB\-\-verbose\fP
.RS 4
Explain what is being done.
.RE
.sp
\fB\-h\fP, \fB\-\-help\fP
.RS 4
Display help text and exit.
.RE
.sp
\fB\-V\fP, \fB\-\-version\fP
.RS 4
Display version and exit.
.RE
.SH "EXIT STATUS"
.sp
The \fBmesg\fP utility exits with one of the following values:
.sp
\fB0\fP
.RS 4
Messages are allowed.
.RE
.sp
\fB1\fP
.RS 4
Messages are not allowed.
.RE
.sp
\fB>1\fP
.RS 4
An error has occurred.
.RE
.SH "FILES"
.sp
\fI/dev/[pt]ty*\fP, \fI/dev/pts/[0\-9]*\fP
.SH "HISTORY"
.sp
\fBmesg\fP (I) appears in the UNIX Programmer\(cqs Manual.
It used to invert the current state with no argument before Version 7 AT&T UNIX.
.SH "SEE ALSO"
.sp
\fBlogin\fP(1),
\fBtalk\fP(1),
\fBwrite\fP(1),
\fBwall\fP(1),
\fBxterm\fP(1)
.SH "REPORTING BUGS"
.sp
For bug reports, use the \c
.URL "https://github.com/util\-linux/util\-linux/issues" "issue tracker" "."
.SH "AVAILABILITY"
.sp
The \fBmesg\fP command is part of the util\-linux package which can be downloaded from \c
.URL "https://www.kernel.org/pub/linux/utils/util\-linux/" "Linux Kernel Archive" "."
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