netstat -nap|grep 3000
# returns list process using port 3000 last column show id of this process
# tcp 0 0 127.0.0.1:3000 0.0.0.0:* LISTEN 11249/node
# tcp 0 0 127.0.0.1:3000 127.0.0.1:35804 ESTABLISHED 11249/node
# tcp 0 0 127.0.0.1:35804 127.0.0.1:3000 ESTABLISHED 2392/chrome --type=
# tcp 0 0 127.0.0.1:3000 127.0.0.1:35746 ESTABLISHED 11249/node
# tcp 0 0 127.0.0.1:35878 127.0.0.1:3000 ESTABLISHED 2392/chrome --type=
# tcp 0 0 127.0.0.1:3000 127.0.0.1:35878 ESTABLISHED 11249/node
# tcp 0 0 127.0.0.1:35746 127.0.0.1:3000 ESTABLISHED 2392/chrome --type=
kill -9 11249
#kills process 11249