#!/usr/bin/perl -w
use URI::Escape;
use HTML::Entities;
use CGI qw/:standard/;
print "Content-type: text/html\n\n";
my $file;
if(param('test')){
        my $code = param('test');
        $code = uri_unescape($code);
        $code = encode_entities($code);
        open STDERR, '>&STDOUT';
                open my $fh, '>', \$file;
                print $fh $code;
                close $fh;
                open my $pipe, '-|', "perl -w $file";
                close $pipe;
        close STDERR;
}

##</code><code>##

sh: -c: line 0: syntax error near unexpected token `;;'
sh: -c: line 0: `perl -w print "hi";'

##</code><code>##

print "hi";
print "hello world\n";