Does a string pattern on subject SUBJ.  Returns 1.0 if the pattern
exists anywhere within SUBJ, and 0.0 if the pattern does not exist
within SUBJ.  The pattern PAT can be any regular expression, as
described in the Unix manual page on regex(5), with the following
exception: the $n notation does not work, as there are no return
values from this function.  Note that the pattern does not need to
start in the first character of SUBJ, unless the pattern begins
with the ^ (beginning of string) character.

Pattern to use for the match.  It can be any regular expression.

String to search for match.

Returns 1 if PAT exists anywhere within SUBJ,
and 0 if PAT does not exist within SUBJ.