wall (Unix)
{{Short description|Unix command-line messaging utility}}
{{lowercase}}
{{Infobox Software
| name = wall
| logo =
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| developer = AT&T Bell Laboratories
| released = {{Start date and age|1975|5}}
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| operating system = Unix and Unix-like
| genre = Command
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}}
{{mono|wall}} (an abbreviation of write to all) is a Unix command-line utility that displays the contents of a computer file or standard input to all logged-in users. It is typically used by root to send out shutting down message to all users just before poweroff.
Invocation
{{mono|wall}} reads the message from standard input by default when the filename is omitted. This is done by piping the output of the {{mono|echo}} 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 {{mono|cat}} is used: invoking {{mono|wall}} by typing {{kbd|wall}} and pressing {{keypress|Enter}} followed by a message, pressing {{keypress|Enter}} and End-of-transmission character:
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(1)):
Broadcast Message from alice@sleipnir
(/dev/pts/7) at 16:15 ...
Remember to brush your teeth!
See also
References
{{Reflist}}
- {{man|1|wall|v7}}
- {{man|1|wall|die.net}}
- {{man|1|wall|FreeBSD}}
- {{man|8|wall|Solaris}}
{{Unix commands}}