I want to move to a line some(say 3) lines back

Fellow Monk,
Consider the following:

use Tie::File;
   | 
   | 
sub moveLineInFile {
     my ($fname,$lineFrom,$lineTo)=@_;
     my @ry=();

     tie @ry,'Tie::File',"fname" or die "$fname: $!";

     my $temp = $ry[$lineFrom];
     for ( my $ix=$lineFrom;$ix>$lineTo;$ix++){
       $ry[$ix]=$ry[$ix-1];
     }
     $ry[$lineFrom]=$temp;
    untie @ry;
}
[download]

A couple of caveats here: first off make sure you understand for instance that if you want to move line 10 to line 6 in file "foo.txt" you'd invoke the above sub as moveLineInFile('foo.txt',9,5). There are no doubt more efficient ways of doing this but I chose to show you this way so you can see the concept of what is going on here more transparently. Sorta like "The Visible Man" models of my youth. Don't know if those are still around or even if that's a culture centric reference.

My last comment is to echo what other monks have told you in this thread. It is customary here at the Monastery to follow up on a question you asked by posting a reply to your own post rather than starting a new thread.

Also, something that I preach to students and co-workers of mine a very important concept: Problem Definition

When you ask a question here at Perl Monks (or any other forum for that matter) make sure you have the entire problem well defined before asking. This way folks can understand what it is you are trying to do and can give you the solution you need rather than unecessary detours along the way.

Sorta reminds me of a story that has been bandied about for a while about the fellow who calls a help desk to say that his computer doesn't work. The punch line to the story (won't tell the whole thing here) is that there was a blackout and that's why the computer didn't work!