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FNMATCH(3P) POSIX Programmer's Manual FNMATCH(3P)


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.


fnmatch — match a filename string or a pathname


#include <fnmatch.h>
int fnmatch(const char *pattern, const char *string, int flags);


The fnmatch() function shall match patterns as described in the Shell and Utilities volume of POSIX.1‐2017, Section 2.13.1, Patterns Matching a Single Character and Section 2.13.2, Patterns Matching Multiple Characters. It checks the string specified by the string argument to see if it matches the pattern specified by the pattern argument.

The flags argument shall modify the interpretation of pattern and string. It is the bitwise-inclusive OR of zero or more of the flags defined in <fnmatch.h>. If the FNM_PATHNAME flag is set in flags, then a <slash> character ('/') in string shall be explicitly matched by a <slash> in pattern; it shall not be matched by either the <asterisk> or <question-mark> special characters, nor by a bracket expression. If the FNM_PATHNAME flag is not set, the <slash> character shall be treated as an ordinary character.

If FNM_NOESCAPE is not set in flags, a <backslash> character in pattern followed by any other character shall match that second character in string. In particular, "\\" shall match a <backslash> in string. If pattern ends with an unescaped <backslash>, fnmatch() shall return a non-zero value (indicating either no match or an error). If FNM_NOESCAPE is set, a <backslash> character shall be treated as an ordinary character.

If FNM_PERIOD is set in flags, then a leading <period> ('.') in string shall match a <period> in pattern; as described by rule 2 in the Shell and Utilities volume of POSIX.1‐2017, Section 2.13.3, Patterns Used for Filename Expansion where the location of ``leading'' is indicated by the value of FNM_PATHNAME:

If FNM_PATHNAME is set, a <period> is ``leading'' if it is the first character in string or if it immediately follows a <slash>.
If FNM_PATHNAME is not set, a <period> is ``leading'' only if it is the first character of string.

If FNM_PERIOD is not set, then no special restrictions are placed on matching a period.


If string matches the pattern specified by pattern, then fnmatch() shall return 0. If there is no match, fnmatch() shall return FNM_NOMATCH, which is defined in <fnmatch.h>. If an error occurs, fnmatch() shall return another non-zero value.


No errors are defined.

The following sections are informative.




The fnmatch() function has two major uses. It could be used by an application or utility that needs to read a directory and apply a pattern against each entry. The find utility is an example of this. It can also be used by the pax utility to process its pattern operands, or by applications that need to match strings in a similar manner.

The name fnmatch() is intended to imply filename match, rather than pathname match. The default action of this function is to match filename strings, rather than pathnames, since it gives no special significance to the <slash> character. With the FNM_PATHNAME flag, fnmatch() does match pathnames, but without tilde expansion, parameter expansion, or special treatment for a <period> at the beginning of a filename.


This function replaced the REG_FILENAME flag of regcomp() in early proposals of this volume of POSIX.1‐2017. It provides virtually the same functionality as the regcomp() and regexec() functions using the REG_FILENAME and REG_FSLASH flags (the REG_FSLASH flag was proposed for regcomp(), and would have had the opposite effect from FNM_PATHNAME), but with a simpler function and less system overhead.




glob(), Section 2.6, Word Expansions

The Base Definitions volume of POSIX.1‐2017, <fnmatch.h>


Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at .

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2017 IEEE/The Open Group