getopt_long_only(3)

💖 getopt_long_only(3) — like, the manual page, bestie 💖

okay so this is getopt_long_only, straight outta the Library Functions Manual (yep, section 3, that's the "C library functions" section, iykyk). she parses long command-line options and she does it differently than her sister. let's get into it 🌸

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✨ NAME ✨

getopt_long_only — parse long command-line options 👑

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🎀 LIBRARY 🎀

Standard C library, aka libc, link it with -lc. she's literally built in, no third-party nonsense 💅

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🌈 SYNOPSIS 🌈

#define _GNU_SOURCE
#include <getopt.h>

int getopt_long_only(int argc, char *argv[],
           const char *optstring,
           const struct option *longopts, int *longindex);

⚠️ bestie look at that #define _GNU_SOURCE — you need it, she's a GNU girl, she does not show up without it 🙈

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🦋 DESCRIPTION 🦋

so getopt_long_only() is basically getopt_long(3)'s twin sister, but with one chaotic little twist: both - AND -- can signal a long option. that's it, that's the whole plot. main character behavior honestly ✨

and here's the fine print: if an option starts with just a single - (so, not --) and it doesn't match a long option, but it does match a short one? then she goes "oh ok, we're doing short options now" and parses it as a short option instead. flexible queen 🫶

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💜 ATTRIBUTES 💜

for the deets on what these words even mean, go read attributes(7). no cap.

• Interface: getopt_long_only()
• Attribute: Thread safety
• Value: MT-Unsafe race:getopt env

😭 ok so translate that: she is MT-Unsafe, there's literally a race on getopt, and she touches env. multiple threads + this function = messy. don't do it. not her fault, that's just the vibe 💀

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⭐ STANDARDS ⭐

GNU. (of course. she's got that GNU energy, that's literally the whole point 🧚)

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👑 SEE ALSO 👑

• getopt(1)
• getopt(3)
• getopt_long(3)
• getsubopt(3)

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and that's the whole page, bestie, you ate it 💅✨

this was brought to you by Linux man-pages 6.20, dated 2025-12-07 — mwah, love you, now go write some --long-options 🍓💖🎀