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(elisp)Syntax of Regexps

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Syntax of Regular Expressions
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   Regular expressions have a syntax in which a few characters are
special constructs and the rest are "ordinary".  An ordinary character
is a simple regular expression that matches that character and nothing
else.  The special characters are `.', `*', `+', `?', `[', `]', `^',
`$', and `\'; no new special characters will be defined in the future.
Any other character appearing in a regular expression is ordinary,
unless a `\' precedes it.

   For example, `f' is not a special character, so it is ordinary, and
therefore `f' is a regular expression that matches the string `f' and
no other string.  (It does _not_ match the string `fg', but it does
match a _part_ of that string.)  Likewise, `o' is a regular expression
that matches only `o'.

   Any two regular expressions A and B can be concatenated.  The result
is a regular expression that matches a string if A matches some amount
of the beginning of that string and B matches the rest of the string.

   As a simple example, we can concatenate the regular expressions `f'
and `o' to get the regular expression `fo', which matches only the
string `fo'.  Still trivial.  To do something more powerful, you need
to use one of the special regular expression constructs.

Regexp Special

Special characters in regular expressions.

Char Classes

Character classes used in regular expressions.

Regexp Backslash

Backslash-sequences in regular expressions.