The fact that plain parentheses fulfil two functions is notThe fact that plain parentheses fulfil two functions is not always helpful.
For example, if you want to match a "*" character, you write "\*" in the pattern. This applies whether or not the follow- ing character would otherwise be interpreted as a meta- character, so it is always safe to precede a non-alphanumeric with "\" to specify that it stands for itself. In particu- lar, if you want to match a backslash, you write "\\".