SAVE-ENTROPY(8)

📦 version 15.1, in freebsd 14.5, freebsd 15.1

💾 save-entropy(8) — the group-chat edition 💅

okay so bestie, picture this: it's section 8 of the system manager's manual, and we're talking about the little script that tucks entropy away so your system has something to sip on at boot. iconic behaviour, honestly.

✨ NAME ✨

save-entropy — saving bits of entropy so /dev/random gets fed at startup 🍼✨

🎀 SYNOPSIS 🎀

save-entropy

that's it. no flags, no drama. she takes zero arguments and she serves. periodt.

🌸 DESCRIPTION 🌸

so save-entropy is the command that takes entropy data from /dev/random and saves it into files in a specified output location. those saved files get used at startup to give /dev/random some extra entropy to work with — like leaving snacks out for your future self, lowkey genius 🫶

the output file will be different in every invocation until the maximum number of different files is reached (see entropy_save_num for the details, bestie — she's the one who keeps count). by default this script is invoked via cron(8) roughly every eleven minutes. every eleven minutes! she's committed 😭💖

heads up: this command does nothing if executed inside a jail(8). jails get no entropy-saving slay, that's just the rules 🙈

three variables in /etc/rc.conf regulate how this script behaves, and you need to know them:

  • entropy_dir — specifies the directory for the saved entropy files. defaults to /var/db/entropy. if you set it to "NO" it disables caching entropy via cron(8). this setting is shared with /etc/rc.d/random, so like, don't be surprised when they both react 👀
  • entropy_save_sz — the size of the entropy cache files. defaults to 4096.
  • entropy_save_num — the number of entropy cache files to save. defaults to 8.

🦋 FILES 🦋

  • /etc/rc.conf

(the main character config file, obviously 👑)

💀 EXIT STATUS 💀

save-entropy exits 0 on success, and >0 if an error occurs. and ngl, errors don't just vanish — they get recorded in the system log. receipts are kept, fr fr 📝

🌈 SEE ALSO 🌈

go read them, iykyk 💜

⭐ HISTORY ⭐

the save-entropy command first appeared in FreeBSD 5.0. a legend from the jump 🧚✨

💖 AUTHORS 💖

the save-entropy command was originally written by Doug Barton <dougb@FreeBSD.org>. and this manual page was written by Fernando Apesteguia <fernape@FreeBSD.org>. absolute icons, both of them 🫶👑

and that's the whole page, bestie 🎀 this one's from the Debian crew — dated September 18, 2023 — and it lives in section 8, the system manager's manual. go save some entropy, you deserve it 💅✨

📦 where this page comes from