#!/usr/bin/perl
# This is a PERL script.
# First it removes all lines consisting of \n only.
# Then it adds one blank line after every line.
# commandline contains input file name(s).
# Output to standard output.
# You should use output redirection.
while ($_ = <ARGV>)
  {
      s/^\n//;       # Removes all lines of  "\n"  only.  
      s/\n/\n\n/;  # Adds a blank line after every line.
      print $_;
  }
# Excercise for students: Figure out this code.