Processes and ports: list what’s running, kill by port

Useful commands to see which process is using a port and to free it.

See what’s using a port

macOS / Linux (lsof):

# Process listening on port 8080
lsof -i :8080

# Same, alternative syntax
lsof -i TCP:8080

Example output:

COMMAND   PID USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
java    12345  you   42u  IPv6 0x...      0t0  TCP *:8080 (LISTEN)

The PID is what you need to kill.

Get only the PID

# Just the PID for port 8080 (handy for scripts)
lsof -t -i :8080

Kill the process on a port

One-liner (macOS / Linux):

# Kill whatever is on 8080 (sends SIGTERM)
kill $(lsof -t -i :8080)

Multiple ports (one-liner):

# Kill whatever is on 8080 and 3000 (sends SIGTERM)
kill $(lsof -t -i :8080 -i :3000) 2>/dev/null

# Same, comma-separated ports (shorter)
kill $(lsof -ti :3000,8080) 2>/dev/null

Add more -i :PORT for more ports, or use a comma-separated list with one -i :port1,port2. 2>/dev/null hides errors when nothing is listening on a port.

Force kill if it doesn’t exit:

kill -9 $(lsof -t -i :8080)

# Multiple ports
kill -9 $(lsof -ti :3000,8080) 2>/dev/null

-9 is SIGKILL (no graceful shutdown).

Kill multiple ports at once

Use the one-liner above, or a loop when you have many ports:

# Free 8080 and 3000 (same as one-liner)
for p in 8080 3000; do kill $(lsof -t -i :$p) 2>/dev/null; done

List your listening ports

# All listening TCP ports
lsof -i -P -n | grep LISTEN

# Only your user’s processes
lsof -i -P -n | grep LISTEN | grep $USER

-P shows port numbers (e.g. 8080 instead of http-alt), -n avoids DNS lookups.

With netstat (often available on Linux):

netstat -tlnp   # TCP, listening, with PID (Linux)
netstat -tln    # macOS (no -p)

Quick reference