#!/usr/bin/perl

my $input = "H2Z_ZDL0.000";
my $ouput = "sorted.txt";

# Open $input for reading.
open(ORIGFILE, "<", $input) 
     or die "Could not open $input: $!";

# Open $output for writing, destroying current file contents
open (FINALFILE, ">", $output) 
     or die "Could not open $output: $!";

# This line does several things.  It reads all the lines 
# from ORIGFILE into memory (which is done in the <ORIGFILE> 
# bit), sorts them (using sort) and then prints them out 
# to the file in FINALFILE.
print FINALFILE sort(<ORIGFILE>);

# close file in FINALFILE, flushes buffer
close (FINALFILE);
# close file in ORIGFILE
close (ORIGFILE);