# $0 contains the name of the running script (ie this one)
# $! contains error messages, if any

# open file for reading
open ME, "<$0" or die "Can't open myself, Perl says $!\n";
my @essence = <ME>;
close ME;

# open file for writing (clobber existing, create if required)
# name will be whatever this script called with .clone extension
open MY, ">$0.clone" or die "Failed to clone myself $!\n";
print MY @essence;
close MY;

# open file for appending (add to end of file)
open CLONE, ">>$0.clone" or die "Clone has disappeared $!\n";
print CLONE "\n\nI am just a clone of the program $0\n";
print CLONE "Just Another Perl Hacker\n", scalar localtime;
close CLONE;