The GNU C Library provides pattern matching facilities for two kinds of patterns: regular expressions and file-name wildcards. The library also provides a facility for expanding variable and command references and parsing text into words in the way the shell does.
| Wildcard Matching | Matching a wildcard pattern against a single string. |
| Globbing | Finding the files that match a wildcard pattern. |
| Regular Expressions | Matching regular expressions against strings. |
| Word Expansion | Expanding shell variables, nested commands, arithmetic, and wildcards. This is what the shell does with shell commands. |