open FILE, '<', $file;
my $nfile = $file . '.new';
open OFILE, '>', $nfile;
while (<FILE>){
        if($_ =~ /STARTING_PATTERN\s+(.*)/){
            $sub=$1;
            s/$sub/$cell_name/ ;
            }
        print OFILE, $_;                                
    }                                        
    close FILE;
    close OFILE;
    rename $file, $file . '.bak';
    rename $nfile, $file;