Help for this page
perl -e 'use strict; my @n = qx!/bin/netstat -a|grep LISTEN|grep -v un +ix; sleep 4!; print $_ . $/ for @n;'
perl -e 'use strict; my @n = system("/bin/netstat -a|grep LISTEN|grep + -v unix; sleep 4"); print $_ . $/ for @n;'