icg,
If I understand correctly, you want to do something with a line if it contains 2 characters but exclude it if they are preceded by a whitespace. Negated character classes to the rescue: 
if ( $line =~ /[^\s]XY/ ) { ... }

[download]
Where XY are the two characters you want. Alternatively, if the whitespace requirement for exclusion is at the beginning of the line you can just do: 
while ( <FILE> ) {
    next if /^\s/;
    # process lines without leading whitespace here ...
}

[download]

Cheers - L~R

In reply to Re: Negating a leading whitespace by Limbic~Region
in thread Negating a leading whitespace by icg

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