1. Useless use of back ticks, try system or exec.

   ...and so your test is probably not doing what you think it is. spoke too soon.

   Or maybe you intended to discard the output as a side-effect, do it explicitly with /dev/null or some such.

2. Why not use the environment variables directly?
3. What if I don't have a $HOME? ;-)

UPDATE:

#Globals are bad mojo
my $remotemachine = $ARGV[0];

# see if keys exist
if (-e !"/$home/.ssh/id_dsa.pub"){
    system('ssh-keygen', '-t', 'dsa');
}
#Only use semi-colon's after do{} blocks.

system('scp', "/$ENV{HOME}/.ssh/id_dsa.pub, "$remotemachine://home/$EN
+V{USER}/.ssh/authorized_keys2");
system('ssh-agent', q(sh -c 'ssh-add < /dev/null && bash'));
exec('ssh', $remotemachine);
#exit (0); #That's the default
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