WRITE(1)
NAME
write − write to another user
USAGE
write node!user [ttyname]
write user@node [ttyname]
DESCRIPTION
The write command copies lines from your node to that of another user. When first called, it sends the following message:
Message from yournode!yourname [yourttyname] ...
The recipient of the message should write back at this point. Communication continues until an end-of-file (EOF) is read from the terminal, or an interrupt is sent. At that point, the write program writes “EOT” on the other terminal and exits.
To write to a user who is logged in more than once, use the ttyname argument to indicate the appropriate terminal name.
If write finds an exclamation point (!) at the beginning of a line, it calls the shell to execute the rest of the line as a command.
When you first write to a user, wait for a reply before sending another message. Each party should end each message with a distinctive signal, such as (o) for “over”, or (oo) for “over and out” (when you want to terminate the conversation).
To enable a write to a node other than your own, the recipient node must be running the write program daemon (writed(8C)), as well as an mbx_helper program. Similarly, you must be running writed on your node to receive messages from someone on another node. The mbx_helper is a program residing in the /sys/mbx directory of your node. When it is run, it allows your node to handle interprocess communications with other nodes in your network also running mbx_helper.
FILES
/etc/utmp record of who is logged in on the node (link to ‘node_data/etc.utmp)
/bin/sh to execute “!”