Other Escape Sequences and Assertions

Other escape sequences

To match a literal instance of a metacharacter, escape it with a backslash \. We’ve seen this before, where \( refers to a single left parenthesis and \] refers to a single right square bracket. \. refers to a literal period character instead of the “match anything but an explicit newline character” atom.

Remember to escape the alternation metacharacter |, as well as the end-of-line metacharacter $ and the quantifiers +, ?, and * if you want to match their symbols literally.

The metacharacter disabling characters (\Q and \E) disable metacharacter interpretation within their boundaries. This is especially useful when we don’t control the source of the matched text: