pl
Perl One-Liner Magic Wand
...And same, SHOUTING:
$ pl -opl '' Perl one-liner
$ pl -opl '$_ = uc' Perl one-liner
Print up to 3 matching lines, resetting count (and "$.") for each file:
$ pl -rP3 '/Perl.*one.*liner/' file*
Count hits in magic statistics hash "%N(UMBER)":
$ pl -n '++$N{$1} while /(Perl|one|liner)/g' file*