fnmatch(3)

✨ fnmatch — bestie edition ✨

okay so real talk, this is from the Library Functions Manual — it's fnmatch(3) and she is THAT girl of shell wildcard matching. let's get into it 💅

---

🌸 NAME 🌸

fnmatch — match filename or pathname.

no cap, that's the whole job. she looks at a string and tells you if it vibes with a pattern. 🦋

---

📚 LIBRARY 📚

Standard C library: libc, -lc. your fave, literally always there for you 🫶

---

✨ SYNOPSIS ✨

#include <fnmatch.h>

int fnmatch(const char *pattern, const char *string, int flags);

three args, zero drama. she's lowkey elegant like that 😌

---

💖 DESCRIPTION 💖

so. the fnmatch() function checks whether the string argument matches the pattern argument — and that pattern is a shell wildcard pattern (peep glob(7) for the deets, iykyk 👀).

the flags argument is what changes her behavior, and bestie it is the bitwise OR of zero or more of the following flags. zero. or more. you pick, she's flexible 💅

• FNM_NOESCAPE — when this one's set, a backslash is just a regular character doing regular character things, not an escape character. she's retiring, your honor 🎀
• FNM_PATHNAME — set this and a slash in string can only be matched by a slash in pattern. not by an asterisk (*), not by a question mark (?), and not by a bracket expression ([]) that contains a slash. slashes stay exclusive, periodt 🔒
• FNM_PERIOD — set this and a leading period in string has to be matched exactly by a period in pattern. and what counts as "leading"? a period is leading if it's the first character in string, or if both FNM_PATHNAME is set and the period immediately follows a slash. dotfiles are picky, respect her boundaries 🙈
• FNM_FILE_NAME — this is a GNU synonym for FNM_PATHNAME. same girl, different name 😭
• FNM_LEADING_DIR — this one's a GNU extension. set it and the pattern counts as matched if it matches an initial segment of string that is followed by a slash. also important: this flag is mainly for the internal use of glibc and is implemented only in certain cases. so like, don't build your whole personality on it 💀
• FNM_CASEFOLD / FNM_IGNORECASE (same as FNM_CASEFOLD) — set this and the pattern is matched case-insensitively. no uppercase slander here, every letter is welcome 🌈
• FNM_EXTMATCH — a GNU extension. set it and extended patterns are supported — as introduced by 'ksh' and now supported by other shells. the extended format goes like this, where pattern-list is a '|'-separated list of patterns 👑
• '?(pattern-list)' — the pattern matches if zero or one occurrences of any of the patterns in the pattern-list match the input string.
• '*(pattern-list)' — the pattern matches if zero or more occurrences of any of the patterns in the pattern-list match the input string.
• '+(pattern-list)' — the pattern matches if one or more occurrences of any of the patterns in the pattern-list match the input string.
• '@(pattern-list)' — the pattern matches if exactly one occurrence of any of the patterns in the pattern-list match the input string.
• '!(pattern-list)' — the pattern matches if the input string cannot be matched with any of the patterns in the pattern-list. the hater of the group, and we love her for it 💀✨

---

🎯 RETURN VALUE 🎯

• Zero if string matches pattern — slay, we love a clean zero 💚
• FNM_NOMATCH if there's no match 😭
• another nonzero value if there's an error. so like… not every nonzero is FNM_NOMATCH, check before you spiral fr fr

---

🧵 ATTRIBUTES 🧵

for an explanation of the terms used in this section, go see attributes(7).

• Interface: fnmatch()
• Attribute: Thread safety
• Value: MT-Safe env locale

(that was a table in the original, bestie — we're just vibing in bullets now 🎀)

---

📜 STANDARDS 📜

• fnmatch() — POSIX.1-2008.
• FNM_CASEFOLD, FNM_IGNORECASE — POSIX.1-2024.
• FNM_FILE_NAME, FNM_LEADING_DIR — GNU.

---

🕰️ HISTORY 🕰️

• fnmatch() — POSIX.1-2001, POSIX.2.
• FNM_CASEFOLD — has been available on many systems even before POSIX.1-2024. she was an icon before the paperwork caught up, iconic behavior 👑

---

👀 SEE ALSO 👀

sh(1), glob(3), scandir(3), wordexp(3), glob(7)

---

and that's the whole page, bestie — go match some strings, treat backslashes with respect, and don't forget that FNM_LEADING_DIR is glibc-internal and only implemented in certain cases 😭💅

this has been Linux man-pages 6.20, dated 2026-02-08, page fnmatch(3) 🌸 stay matching, stay MT-Safe 🫶✨