COMSAT(8)

💌 COMSAT — the biff server, bestie edition 💌

okay so picture this: it's comsat(8), and it's literally the girl in the group chat whose entire job is to yell "BESTIE YOU GOT MAIL 📬" the second something lands in your inbox. iconic behavior honestly.

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✨ NAME ✨

comsat — the biff server 🎀

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✨ SYNOPSIS ✨

comsat

that's it. no args. no flags. she simply exists and does her thing 💅

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✨ DESCRIPTION ✨

so comsat is the server process that catches incoming-mail reports and then notifies users — but ONLY if those users asked for this service in the first place. no consent, no notifications, we respect boundaries here 🫶

she receives her messages on a datagram port that's tied to the "biff" service specification (go peek at services(5) and inetd(8) if you wanna see the receipts).

the messages are one-liners, and they look exactly like this:

user@mailbox-offset:/path/to/mailbox

now here's the vibe check 👀 — if the user named in that line is logged in to the system and the terminal they're on has the owner execute bit turned on (which happens when someone runs a "biff y"), then the offset gets used as a seek offset into the right mailbox file, and the first 7 lines or 560 characters of the message get printed straight onto that user's terminal. slay.

one lil caveat tho: any lines that look like they're part of the message header — except the "From" and "Subject" lines — do NOT make it into the output. she's picky like that 💅

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✨ FILES ✨

• /var/run/utmp — she reads this to figure out who's logged on and on which terminals 🌸 (it's giving surveillance but make it cozy)

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✨ SEE ALSO ✨

• biff(1)
• inetd(8)

go read those, they're the supporting cast 🦋

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✨ BUGS ✨

okay bestie, we gotta be real for a sec 😭

• the message header filtering? prone to error. she tries her best but she's not perfect fr fr.
• the density of information presented is near the theoretical minimum. that's the actual wording and honestly it's so shady of whoever wrote it but it's true 💀
• users should be notified of mail that arrives on other machines than the one they're currently logged in to. like, cross-machine mail exists, hello?? 🙈
• the notification should appear in a separate window so it doesn't mess up the screen. (retro terminal girls, we hear you 👑)

and if you find bugs, please report them to netbug@ftp.uk.linux.org — and pls pls pls include diffs/patches, compiler error logs, or just as complete a bug report as you're able to put together. give her something to work with, she's begging 🥺

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✨ HISTORY ✨

the comsat daemon first appeared in 4.2BSD. she's been doing this since before your parents had email ⭐

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💖 and that's the whole page bestie — Linux NetKit (0.17-pre-20000412), dated July 31, 1999. she's an elder but she still serves. periodt. 💅✨🌸