write(1)
Name
write − write message to another user
Syntax
write user [ttyname]
Description
The write command copies lines from your terminal to that of another user. When first called, it sends the message
Message from yoursystem!yourname yourttyname...
The recipient of the message should write back at this point. Communication continues until an end of file is read from the terminal or an interrupt is sent. At that point write writes ‘EOT’ on the other terminal and exits.
If you want to write to a user who is logged in more than once, the ttyname argument may be used to indicate the appropriate terminal name.
Permission to write may be denied or granted by use of the mesg command. At the outset writing is allowed. Certain commands, in particular nroff and pr() disallow messages in order to prevent messy output.
If the character ‘!’ is found at the beginning of a line, write calls the shell to execute the rest of the line as a command.
The following protocol is suggested for using write: when you first write to another user, wait for him to write back before starting to send. Each party should end each message with a distinctive signal. The letter ‘o’ is the convention for ‘over’ which indicates that the message is complete. The letters ‘oo’ are the convention for ‘over and out’ which is used when the conversation is about to be terminated.
Files
/etc/utmpto find user
/bin/shto execute ‘!’