Usage:
 wall [options] [<file> | <message>]

Write a message to all users.

Options:
 -g, --group <group>     only send message to group
 -n, --nobanner          do not print banner, works only for root
 -t, --timeout <timeout> write timeout in seconds

 -h, --help              display this help
 -V, --version           display version

For more details see wall(1).