A quick way to see which dev servers are running locally

I sometimes have a few projects going at the same time. Most of them are running some kind of server. And at some point, one of them won’t start because a port is already taken.

At that moment, I usually don’t know which project is using it.

I could use lsof and search by a specific port, but that assumes I already know which port I’m looking for. What I really wanted instead was a quick way to see all active servers at once, without guessing first.

I also didn’t want to see every background system service macOS happens to be running. I only care about servers I actually started — node, python, things like that.

So I wrote a small bash script that does exactly that.

I just type:

servers

and it shows me a list of:

• ports
• PIDs
• commands
• and the folder the server was started from (which is basically the project)

Once I see the one I care about, I kill the PID and I’m done.

No guessing. No hunting. No “what is even running right now?”

The script

Create a file called servers:

nano ~/scripts/servers

Paste this in:

#!/usr/bin/env bash

echo "PORT    PID      COMMAND              PROJECT"
echo "----------------------------------------------------"

lsof -iTCP -sTCP:LISTEN -n -P | awk 'NR>1 {print $2, $9}' \
| awk '
  {
    pid=$1
    addr=$2
    port=addr
    sub(/^.*:/,"",port)
    key=pid ":" port
    if (!seen[key]++) print pid, port
  }
' \
| while read -r pid port; do
    cmd=$(ps -p "$pid" -o comm= 2>/dev/null)
    cwd=$(lsof -p "$pid" 2>/dev/null | awk '$4=="cwd" {print $9; exit}')
    printf "%-7s %-8s %-20s %s\n" "$port" "$pid" "$cmd" "${cwd:-/}"
  done \
| sort -n

Make it executable:

chmod +x ~/scripts/servers

Make it available everywhere (zsh)

In ~/.zshrc, add:

export PATH="$HOME/scripts:$PATH"

Reload:

source ~/.zshrc

How I use it

When something won’t start:

servers

See the PID I care about, then:

kill <PID>

That’s it.

It’s a tiny script, but it removed a recurring bit of friction. Instead of reacting to port conflicts, I can just see what’s running and move on.