Can you find anything wrong? It is run on a UNIX server:
#
# shows who is logged on to the server
#
#!/usr/bin/perl
use CGI::Carp qw(fatalsToBrowser);
print "Content-type: text/html\n\n";
my $who_cmd = ''bin/who'';
my &who = `$who_cmd`;
print <
Who is on the server
Who is on the server
$who
</body>
</html>
EOM
exit;