(an abbreviation of write to all) is a

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, an ...

command-line A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invoking executables and pro ...

utility that displays the contents of a

computer file A computer file is a computer resource for recording data in a computer storage device, primarily identified by its file name. Just as words can be written to paper, so can data be written to a computer file. Files can be shared with and trans ...

standard input In computer programming, standard streams are interconnected input and output communication channels between a computer program and its environment when it begins execution. The three input/output (I/O) connections are called standard input (stdin ...

to all logged-in users. It is typically used by root to send out shutting down message to all users just before poweroff.

Invocation

reads the message from

by default when the filename is omitted. This is done by

piping Within industry, piping is a system of pipes used to convey fluids (liquids and gases) from one location to another. The engineering discipline of piping design studies the efficient transport of fluid. Industrial process piping (and accompa ...

the output of the command: alice@sleipnir:~$ # `tty` to show the current terminal name alice@sleipnir:~$ tty /dev/pts/7 alice@sleipnir:~$ echo Remember to brush your teeth! , wall The message may also be typed in much the same way is used: invoking by typing and pressing followed by a message, pressing and +: alice@sleipnir:~$ wall Remember to brush your teeth! ^D Using a here-string: alice@sleipnir:~$ wall <<< 'Remember to brush your teeth!' Reading from a file is also supported: alice@sleipnir:~$ cat .important_announcement Remember to brush your teeth! alice@sleipnir:~$ wall .important_announcement # same as `wall !$` All the commands above should display the following output on terminals that users allow write access to (see

mesg 


mesg is a Unix command that sets or reports the permission other users have to write to the current user's terminal using the  talk and write commands.
 Usage
It is invoked as:


mesg  n

The 'y' and 'n'  options respectively allow and disallow w ...
(1)

): Broadcast Message from alice@sleipnir (/dev/pts/7) at 16:15 ... Remember to brush your teeth!

References

* * * * {{Unix commands Unix user management and support-related utilities

Invocation

See also

References