UNIX sort

sortRequestFiles("/tmp/input");

sub sortRequestFiles {

$INPUT_DIR = $_[0];

my @files = glob( "$INPUT_DIR/request*" );

foreach (@files ){

   print "Sorting " . $_ . "\n";

   qx/head -n1 $_ > $_.tmp/;

    qx/tail -n +2 $_ | sort -k1,1 -nk2 >> $_.tmp/;

    qx/mv $_.tmp $_/;

  

    }

           }