UUID_UNPARSE(3)

💫 NAME 💫

ok so this is UUID_UNPARSE from section 3 of the programmers manual (iykyk, that's the library-functions girlies) — and bestie, it's literally the glow-up page. uuid_unparse takes a UUID and converts it from its binary representation into a string. from goblin-mode bytes to cute lil readable text. slay. 💅

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✨ SYNOPSIS ✨

#include <uuid.h>

void uuid_unparse(const uuid_t uu, char *out);
void uuid_unparse_upper(const uuid_t uu, char *out);
void uuid_unparse_lower(const uuid_t uu, char *out);

three functions, one header, zero drama 🫶

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🦋 DESCRIPTION 🦋

okay so uuid_unparse() takes the UUID you handed it in uu and converts it from the binary representation into a 36-byte string (plus a trailing '\0', don't forget the '\0' bestie, that's her little bow 🎀) and it looks like this:

1b4e28ba-2fa1-11d2-883f-0016d3cca427

and then it stores that value in the character string pointed to by out. iconic behavior honestly.

here's the tea tho — the case of the hex digits that uuid_unparse() returns may be upper or lower case, and it's dependent on the system-dependent local default. so like, it's giving whatever your system woke up feeling like that day 😭 not me relying on vibes for hex casing.

so if the case of the hex digits actually matters to you (valid, real, we support you), that's exactly what these two are for:

• uuid_unparse_upper() — unparses it and you get UPPERCASE hex digits, no guessing, no chaos 🌸
• uuid_unparse_lower() — unparses it and you get lowercase hex digits, consistent, calm, demure 💜

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👑 CONFORMING TO 👑

this library unparses UUIDs that are compatible with OSF DCE 1.1. she's certified, she's vetted, she's got her papers in order 📜✨

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🌈 AUTHORS 🌈

Theodore Y. Ts'o — the main character who made this happen 🫶

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💖 SEE ALSO 💖

the whole friend group, fr fr:

• uuid(3)
• uuid_clear(3)
• uuid_compare(3)
• uuid_copy(3)
• uuid_generate(3)
• uuid_time(3)
• uuid_is_null(3)
• uuid_parse(3)

go say hi to all of them, they're literally so useful 🧚

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🐛 REPORTING BUGS 🐛

found a bug? sad but valid. for bug reports, use the issue tracker at <https://github.com/util-linux/util-linux/issues> — drop the link, tell them what happened, and be nice to the maintainers 💀🙈

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⭐ AVAILABILITY ⭐

the libuuid library is part of the util-linux package since version 2.15.1. it can be downloaded from the Linux Kernel Archive at <https://www.kernel.org/pub/linux/utils/util-linux/> — go get her 💅🔥

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and that's the whole page bestie, every flag, every byte, every casing crisis included, no cap 🎀

okay bye, this was UUID_UNPARSE(3), brought to you by util-linux 2.41.6, dated 2026-08-31 — mwah 💋✨🍓