Hello WWq, and welcome to the Monastery!

To expand on the reply from Loops:

There are a number of problems with the code as posted. First, it is incomplete: FILE1, FILE2, NL, and especially $line3 are used without being declared or initialised. Do you use strict and use warnings at the top of your code?

Second, the array @arr3 is cleared (by being reset to @emptyarr) each time the condition evaluates to true within the first foreach loop. So, after leaving that loop, @arr3 can never contain more than one element. That is, the second foreach loop can have at most one iteration.

Now to two matters of style: (1) Variables should be declared as close as possible to the point of first use. In particular, your loop variables can safely be declared like this:

foreach my $line (@arr2) {
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(2) Code should be indented to make it easy to see where each structure begins and ends. For example:

foreach my $line2 (@arr3) {
    foreach my $line1 (@arr1) {
        if ($line1 =~ m/(.*)\s+(.*)\s+(.*)\s+(.*)\s+(.*)\s+(.*)\s+(.*)
+\s+(.*)/) {
            my $cname1 = "$2";
            if ($cname1 ne $line3) {
                print "$cname1\n"; 
            }
        }
    }
}
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It would also help the monks if you placed your data (the contents of files 1 and 2) within <code> tags, as you’ve done with the code.

To answer your problem, we will need to know what $line3 is supposed to contain.

Hope that helps,