You could use Shell:

use Shell;

my $sh = Shell->new;

my @commands = qw (ls garbage rm);

for (@commands) {
  if ($sh->can($_)) {
    print "command $_ is available\n";
  } else {
    print "command $_ is NOT available\n";
  }
}
[download]

Update: sorry, sorry, this is wrong, I haven't really looked at the output of the script.

---- amphiplex