send a message to another user
allows you to communicate with other
users, by copying lines from your terminal to theirs.
When you run the
command, the user you
are writing to gets a message of the form:
Message from yourname@yourhost on
yourtty at hh:mm ...
Any further lines you enter will be copied to the specified user's terminal. If
the other user wants to reply, they must run
When you are done, type an end-of-file or interrupt character. The other user
will see the message “EOF” indicating that the conversation is
You can prevent people (other than the superuser) from writing to you with the
command. Some commands,
such as pr(1)
, disallow writing
automatically, so that output isn't overwritten.
If the user you want to write to is logged in on more than one terminal, you can
specify which terminal to write to by specifying the terminal name as the
second operand to the
Alternatively, you can let
of the terminals - it will pick the one with the shortest idle time. This is
so that if the user is logged in at work and also dialed up from home, the
message will go to the right place.
The traditional protocol for writing to someone is that the string
“-o”, either at the end of a line or on a line by itself, means
that it's the other person's turn to talk. The string “oo” means
that the person believes the conversation to be over.
write and exit with a zero
utility exits with one of the
- Normal behavior.
- The specified user is either not logged in or not accepting messages.
utility is compliant with the
IEEE Std 1003.1-2008
specification, except that in this
implementation the sender's locale is intentionally ignored in order to avoid
sending characters that the receiving terminal may be unable to display, or
even bytes that might break the receiving terminal's state. Non-ASCII
characters are written as ‘?’.
command appeared in
Version 2 AT&T UNIX
The “EOF” message seen when the other
terminates is indistinguishable from
that party simply typing “EOF” to make you believe that any
future messages did not come from them. Especially messages such as:
 Done rm -rf *