What you need to accomplish this is regular expressions. Learning regular expressions can be a bit painful, but they're really incredibly powerful. As a sample, the code below might give a start point.

The relevant documentation is perlre

open ( my $input_fh, "<", $input_file );
open ( my $output_fh, ">", $output_file );
foreach my $line ( <$input_fh> )
{
  unless ( $line =~ m/\A\s*\Z/ )
  {
    $line =~ s/(GL\d{6}))\d+/$1/;
    print $output_fh $line;
  }
}
close ( $input_fh );
close ( $output_fh );

[download]

The essence is - first you test if a line is blank. Then you use a 'search and replace pattern' to trim any pattern starting GL, followed by 6 digits, to 6 digits.

In reply to Re: Shorten the headers of a file and remove empty lines using perl by Preceptor
in thread Shorten the headers of a file and remove empty lines using perl by intect

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