fnmatch - match a filename string or a pathname
int fnmatch(const char *pattern, const char *string, int flags);
The fnmatch() function shall match patterns as described in XCU Patterns Matching a Single Character and 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 XCU 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 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.
First released in Issue 4. Derived from the ISO POSIX-2 standard.
Moved from POSIX2 C-language Binding to BASE.
POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0154  and XSH/TC1-2008/0155  are applied.
POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0121  is applied.
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