foreach my $fn (qw( /what/ever.file /another/file.txt /third/file/here )) {
    open my $f,'<',$fn or die "Can't open '$fn': $!";
    while (<$f>) { # <-- special case, RTFM
        chomp; # <-- you don't want the newlines, do you?
        if (/interesting/) {
            print "Found in line $. of file '$fn': $_\n";
        }
    }
    close $f;
}