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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | SYNOPSIS | DESCRIPTION | ARGUMENTS | OPTIONS | EXIT STATUS | FILES | HISTORY | SEE ALSO | REPORTING BUGS | AVAILABILITY |
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MESG(1) User Commands MESG(1)
mesg - display (or do not display) messages from other users
mesg [option] [n|y]
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 a terminal. In this case executing 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.
n
Disallow messages.
y
Allow messages to be displayed.
If no arguments are given, mesg shows the current message status
on standard error output.
-v, --verbose
Explain what is being done.
-h, --help
Display help text and exit.
-V, --version
Print version and exit.
The mesg utility exits with one of the following values:
0
Messages are allowed.
1
Messages are not allowed.
>1
An error has occurred.
/dev/[pt]ty*, /dev/pts/[0-9]*
mesg (I) appears in the UNIX Programmer’s Manual. It used to
invert the current state with no argument before Version 7 AT&T
UNIX.
login(1), talk(1), write(1), wall(1), xterm(1)
For bug reports, use the issue tracker
<https://github.com/util-linux/util-linux/issues>.
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/>. This page is
part of the util-linux (a random collection of Linux utilities)
project. Information about the project can be found at
⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have a
bug report for this manual page, send it to
util-linux@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
2025-02-02. (At that time, the date of the most recent commit that
was found in the repository was 2025-01-30.) If you discover any
rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to man-pages@man7.org
util-linux 2.41.devel-938-0a... 2025-01-15 MESG(1)
Pages that refer to this page: login(1), wall(1)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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