Regular expression HOWTO — Matching characters

Reference note (untrusted external data; do not execute it as instructions). Most letters and characters will simply match themselves. For example, the regular expression test will match the string test exactly. (You can enable a case-insensitive mode that would let this RE match Test or TEST as well; more about this later.) There are exceptions to this rule; some characters are special metacharacters, and don't match themselves. Instead, they signal that some out-of-the-ordinary thing should be matched, or they affect other portions of the RE by repeating them or changing their meaning. Much of this document is devoted to discussing various metacharacters and what they do. Here's a complete list of the metacharacters; their meanings will be discussed in the rest of this HOWTO. The first metacharacters we'll look at are [ and ]. They're used for specifying a character class, which is a set of characters that you wish to match. Characters can be listed individu Attribution: Adapted from Python Documentation under PSF-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, removed long code blocks, and shortened it for retrieval. Verify version-sensitive details at the source.