#!perl
use 5.012;

# Populate @ARGV unless files are specified on the command line
@ARGV = grep { -f } glob('/tmp/files/*') unless @ARGV;
while (<>) {
    chomp;
    if ( m/map/i ) {
        # The name of the current file is in the special variable $ARGV
        say "$_ in $ARGV";
    }
}