wall (Unix)

wall

Developer(s)	AT&T Bell Laboratories
Initial release	May 1975(1975-05)
Operating system	UnixandUnix-like
Type	Command

wall(an abbreviation of write to all) is aUnixcommand-lineutility that displays the contents of acomputer fileorstandard inputto all logged-in users. It is typically used by root to send out shutting down message to all users just beforepoweroff.

Invocation

wallreads the message fromstandard inputby default when the filename is omitted. This is done bypipingthe output of theechocommand:

alice@sleipnir:~$ #`tty`toshowthecurrentterminalname
alice@sleipnir:~$tty
/dev/pts/7
alice@sleipnir:~$echoRemembertobrushyourteeth!|wall

The message may also be typed in much the same waycatis used: invokingwallby typingwalland pressing↵ Enterfollowed by a message, pressing↵ EnterandCtrl+D:

alice@sleipnir:~$wall
Remember to brush your teeth!
^D

Using ahere-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 (seemesg(1)):

Broadcast Message from alice@sleipnir
(/dev/pts/7) at 16:15...

Remember to brush your teeth!

See also

• Jordan Hubbard § rwall incident

References

• wall(1)–Version 7 UnixProgrammer'sManual
• wall(1)–LinuxUser CommandsManual
• wall(1)–FreeBSDGeneral CommandsManual
• wall(8)–Solaris 11.4System Administration Commands ReferenceManual