Re^2: Open several files and read line by line

[AnomalousMonk]

while (<$filename>){
    while (/$id1/g && /$id2/g)
    {
        print "$file:$.\n";
    }
}

I don't understand. If  /$id1/g && /$id2/g ever becomes true (matching by default against  $_ assigned in the outer while-loop), when will it ever become false? I.e., isn't this an infinite loop? And what's the point of the  /g modifier in these regexes? And yes,  $filename is a terrible name for a file handle!

Update: I should have known. Many thanks, choroba. (But  $filename is still terrible!)

[choroba]

Without /g it would be an infinite loop. But with /g, the matching starts where the last one stopped:

$_ = "abcabcabc";
while (/c/g && /a/g) {
    say pos;
}

__END__
Output:
4
7