discover active hosts in network

[marek@localhost Dokumenty]$ nmap -sP 192.168.0.0/24

Starting Nmap 6.40 ( http://nmap.org ) at 2014-04-11 22:30 CEST
Nmap scan report for 192.168.0.1
Host is up (0.0064s latency).
Nmap scan report for 192.168.0.10
Host is up (0.0095s latency).
Nmap scan report for 192.168.0.11
Host is up (0.000091s latency).
Nmap done: 256 IP addresses (3 hosts up) scanned in 2.94 seconds