You can execute:
nmap -n -sn 192.168.1.0/24 -oG - | awk '/Up$/{print $2}'
Quick rundown of options and commands:
-n
turns off reverse name resolution, since you just want IP addresses. On a local LAN this is probably the slowest step, too, so you get a good speed boost.-sn
means “Don’t do a port scan.” It’s the same as the older, deprecated-sP
with the mnemonic “ping scan.”-oG -
sends “grepable” output to stdout, which gets piped toawk
./Up$/
selects only lines which end with “Up”, representing hosts that are online.{print $2}
prints the second whitespace-separated field, which is the IP address.