"Search and replace in multiple files with a Perl one-liner" showed how to search multiple files and perform in-line replacements in them, but sometimes you just want to know if a particular file matches something.
perl -ne "exit 1 if m/foobar/;" file1
-n switch causes perl to loop over the lines in the input file without printing them (use
-p for that, as seen in "Search and replace in multiple files with a Perl one-liner"). The
-e switch tells perl an expression to evaluate.
This one-liner will return an exit code of 1 if the file matches, or 0 if there is no match.
Alternatively, if you want to search for matches in multiple files at once you could do this:
perl -ne 'print "match: $ARGV.\n" if m/foobar/;' file1 file2 file3
This would print the name of each matching file (multiple times for multiple matches).