LOCKDEV(8)

💖 LOCKDEV(8) — the manual, but make it make sense 💖

okay bestie, sit down, we're learning lockdev and it's actually gonna be fun.

So lockdev is a setgid binary — yes, setgid, we love a permission moment — and what it gives you is a reliable way to put an exclusive lock in /var/lock on your devices (think ttyS0 and its little friends) using both the FSSTND and the SVr4 methods. And because of that, regular users don't need write access in /var/lock. no cap, that's the whole point. 🎀

And how does it pull this off? Through calls to the liblockdev(3) API. she's built different, fr fr.

✨ SYNOPSIS ✨

/usr/sbin/lockdev [<operation>] <device>

🌸 DESCRIPTION 🌸

So the lockdev command can do one of the following operations (and all of them are calls to the liblockdev(3) API, iykyk):

• -l — lock the device, using the dev_lock() function 🔒
• -u — unlock the device, using the dev_unlock() function 🔓
• no operation — just test the lock, using the dev_testlock() function 👀

👑 RETURN VALUES 👑

exit codes!! and bestie they MATTER, so here's the full vibe check:

• 0 — dev_lock: OK ✨ — dev_unlock: OK ✨ — dev_testlock: not locked
• 1 — dev_lock: locked other — dev_unlock: locked other — dev_testlock: locked
• 2 — EACCES
• 3 — EROFS
• 4 — EFAULT
• 5 — EINVAL
• 6 — ENAMETOOLONG
• 7 — ENOENT
• 8 — ENOTDIR
• 9 — ENOMEM
• 10 — ELOOP
• 11 — EIO
• 12 — EPERM
• 255 — dev_lock: error — dev_unlock: error — dev_testlock: error 💀

not me reading 255 three times like it's gonna change. it doesn't. error is error, bestie. 😭

🦋 SEE ALSO 🦋

• lockdev(3)

okay that's the page!! this one is dated SEPTEMBER 2009 and it lives in the LOCKDEV(8) manual — iconic of her honestly. go forth and lock your devices responsibly. mwah 💅🫶