nscd(8)

📦
version 6.18 · 10 versions
, in alpine 3.24, nixos 26.05

💅 nscd(8) — name service cache daemon 🎀

okay so bestie, welcome to nscd(8) from the System Manager's Manual — yes that's the whole manual section name, we're fancy like that ✨

🌸 NAME 🌸

nscd — the name service cache daemon, aka your lookup bestie that remembers stuff so you don't have to 🧠💖

🦋 SYNOPSIS 🦋

so like, the page doesn't actually give us a synopsis line, but nscd runs as a daemon and takes options — run it and see, iykyk 💅

✨ DESCRIPTION ✨

nscd is a daemon that provides a cache for the most common name service requests. literally its whole job. the default configuration file, /etc/nscd.conf, determines the behavior of the cache daemon — go read nscd.conf(5) for the deets 🫶

nscd provides caching for accesses of the passwd(5), group(5), hosts(5), services(5) and netgroup databases through standard libc interfaces, such as getpwnam(3), getpwuid(3), getgrnam(3), getgrgid(3), gethostbyname(3), and others. the whole crew 🔥

there are two caches for each database, and this part is important:

  • a positive one for items found ✅
  • a negative one for items not found ❌

each cache has a separate TTL (time-to-live) period for its data, so they expire on their own schedule, no cap ⏳

okay so note this: the shadow file is specifically not cached. getspnam(3) calls remain uncached as a result. that's intentional, bestie — your secrets stay un-looked-up 💀🔐

🎀 OPTIONS 🎀

  • --help — will give you a list with all options and what they do. iconic, self-documenting queen 👑

🌈 NOTES 🌈

the daemon will try to watch for changes in configuration files appropriate for each database — like /etc/passwd for the passwd database, or /etc/hosts and /etc/resolv.conf for the hosts database — and flush the cache when these are changed. very main character behavior, she's paying attention 👀✨

but (and this is the catch) this will happen only after a short delay — unless the inotify(7) mechanism is available and glibc 2.9 or later is available. so like, she's fast if she's got the tools, otherwise she's running a little late 🙈

annnd this auto-detection does not cover configuration files required by nonstandard NSS modules, if any are specified in /etc/nsswitch.conf. so if you're doing custom NSS stuff, the auto-vibe-check just doesn't reach it 😭

in that case, you need to run the following command after changing the configuration file of the database so that nscd invalidates its cache:

$ nscd -i <database>
fr fr, do not skip this one — otherwise your cache is out here serving stale info and you're gonna be so confused 💀

💜 SEE ALSO 💜

k that's the whole page, you ate that 💅✨ — this iconic piece of documentation comes from Linux man-pages 6.18, dated 2026-02-08, and honestly? she slays. mwah 🫶🎀

📦 where this page comes from