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10.1 Wildcard Matching

This section describes how to match a wildcard pattern against a particular string. The result is a yes or no answer: does the string fit the pattern or not. The symbols described here are all declared in fnmatch.h.

— Function: int fnmatch (const char *pattern, const char *string, int flags)

This function tests whether the string string matches the pattern pattern. It returns 0 if they do match; otherwise, it returns the nonzero value FNM_NOMATCH. The arguments pattern and string are both strings.

The argument flags is a combination of flag bits that alter the details of matching. See below for a list of the defined flags.

In the GNU C Library, fnmatch cannot experience an “error”—it always returns an answer for whether the match succeeds. However, other implementations of fnmatch might sometimes report “errors”. They would do so by returning nonzero values that are not equal to FNM_NOMATCH.

These are the available flags for the flags argument:

FNM_FILE_NAME
Treat the `/' character specially, for matching file names. If this flag is set, wildcard constructs in pattern cannot match `/' in string. Thus, the only way to match `/' is with an explicit `/' in pattern.
FNM_PATHNAME
This is an alias for FNM_FILE_NAME; it comes from POSIX.2. We don't recommend this name because we don't use the term “pathname” for file names.
FNM_PERIOD
Treat the `.' character specially if it appears at the beginning of string. If this flag is set, wildcard constructs in pattern cannot match `.' as the first character of string.

If you set both FNM_PERIOD and FNM_FILE_NAME, then the special treatment applies to `.' following `/' as well as to `.' at the beginning of string. (The shell uses the FNM_PERIOD and FNM_FILE_NAME flags together for matching file names.)

FNM_NOESCAPE
Don't treat the `\' character specially in patterns. Normally, `\' quotes the following character, turning off its special meaning (if any) so that it matches only itself. When quoting is enabled, the pattern `\?' matches only the string `?', because the question mark in the pattern acts like an ordinary character.

If you use FNM_NOESCAPE, then `\' is an ordinary character.

FNM_LEADING_DIR
Ignore a trailing sequence of characters starting with a `/' in string; that is to say, test whether string starts with a directory name that pattern matches.

If this flag is set, either `foo*' or `foobar' as a pattern would match the string `foobar/frobozz'.

FNM_CASEFOLD
Ignore case in comparing string to pattern.
FNM_EXTMATCH
Recognize beside the normal patterns also the extended patterns introduced in ksh. The patterns are written in the form explained in the following table 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 allow matching the input string.
*(pattern-list)
The pattern matches if zero or more occurrences of any of the patterns in the pattern-list allow matching the input string.
+(pattern-list)
The pattern matches if one or more occurrences of any of the patterns in the pattern-list allow matching the input string.
@(pattern-list)
The pattern matches if exactly one occurrence of any of the patterns in the pattern-list allows matching the input string.
!(pattern-list)
The pattern matches if the input string cannot be matched with any of the patterns in the pattern-list.