Windows

for /L %i in (1,1,254) do @ping -n 1 -w 100 192.168.1.%i >nul && echo 192.168.1.%i is up

Linux

Chatgpt improved:
for i in {1..254}; do (ping -c 1 -W 1 192.168.1.$i > /dev/null 2>&1 && echo "192.168.1.$i is up") & done; wait

Original:
for i in {1..254} ;do (ping -c 1 192.168.1.$i | grep "bytes from" &) ;done

Non thread:
for i in {1..254}; do ping -c 1 -W 1 192.168.1.$i > /dev/null 2>&1 && echo "192.168.1.$i is up"; done