Based on the rest of the OP, I think what you mean is "... find the names of the files in which the file data contains a match to a particular perl regex". Do I have that right?

Some versions of the unix/linux "grep" tool provide an option to apply Perl regex syntax, but it's not clear to me which version of the Perl regex engine would be implemented (i.e. what range of perlish regex extensions is available). If the particular OS you're using has an adequate version of the "grep" utility, then the fastest way to get the file name list you want is to use that version of "grep" at the shell command line, with the relevant option flag.

Apart from that, the only alternative is for your perl script to open each file in the search space, and read the file contents until either (a) the target pattern is found (so you print that file name and move on), or (b) you reach end-of-file (so you just move on to the next file).