MESG(1) User Commands MESG(1)
NAME
mesg - display (or do not display) messages from other users
SYNOPSIS
mesg [option] [n|y]
DESCRIPTION
The 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 talk(1) and write(1) may
display messages on the terminal.
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.
The initial permissions for the terminal are set by login(1) according
to TTYPERM and TTYGROUP from /etc/login.defs. The default is mode 0620
if a tty group is used, and 0600 without the group. The default tty
group name is "tty".
To ensure that your ttys are set in a portable and independent manner
from system settings, mesg should be executed in your login scripts.
mesg modifies the write permissions for a group on the current terminal
device. Since version 2.41, mesg can no longer be compiled to make the
terminal writable for others and strictly modifies only group
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 write(1) or wall(1) to setgid for the "tty" group.
The mesg utility silently exits with error status 2 if not executed on
terminal. In this case execute mesg is pointless. The command line
option --verbose forces mesg to print a warning in this situation. This
behaviour has been introduced in version 2.33.
ARGUMENTS
n
Disallow messages.
y
Allow messages to be displayed.
If no arguments are given, mesg shows the current message status on
standard error output.
OPTIONS
-v, --verbose
Explain what is being done.
-h, --help
Display help text and exit.
-V, --version
Print version and exit.
EXIT STATUS
The mesg utility exits with one of the following values:
0
Messages are allowed.
1
Messages are not allowed.
>1
An error has occurred.
FILES
/dev/[pt]ty[pq]?
HISTORY
A mesg command appeared in Version 6 AT&T UNIX.
SEE ALSO
login(1), talk(1), write(1), wall(1), xterm(1)
REPORTING BUGS
For bug reports, use the issue tracker at
https://github.com/util-linux/util-linux/issues.
AVAILABILITY
The mesg command is part of the util-linux package which can be
downloaded from Linux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.
util-linux 2.38.1 2024-11-21 MESG(1)
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