comsat --- biff server
Comsat is the server process which receives reports of incoming mail and notifies users if they have requested this service. Comsat receives messages on a datagram port associated with the "biff" service specification (see services(5) and inetd(8)). The one line messages are of the form: user@mailbox-offset:/path/to/mailbox If the user specified is logged in to the system and the associated terminal has the owner execute bit turned on (by a "biff y"), the offset is used as a seek offset into the appropriate mailbox file and the first 7 lines or 560 characters of the message are printed on the user's terminal. Lines which appear to be part of the message header other than the "From" or "Subject" lines are not included in the output.
/var/run/utmp to find out who's logged on and on what terminals
The message header filtering is prone to error. The density of the information presented is near the theoretical minimum. Users should be notified of mail which arrives on other machines than the one to which they are currently logged in. The notification should appear in a separate window so it does not mess up the screen. Please report bugs to firstname.lastname@example.org and include diffs/patches, compiler error logs or as complete a bug report as you are able.
The comsat daemon appeared in 4.2BSD.
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