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Daniel Bellmas
Daniel Bellmas

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KillNode Script For React Apps

This is a script to delete a running node process, if one exists.


lsof_output=$(lsof -i :3000)

if [ -n "$lsof_output" ]; then
  node_line=$(echo "$lsof_output" | grep "node")

  if [ -n "$node_line" ]; then
    pid=$(echo "$node_line" | awk '{print $2}')

    # Kill the Node.js process with SIGKILL (9)
    echo "Killing Node.js process with PID $pid"
    kill -9 $pid

    echo "Node.js process killed."
    echo "No Node.js process found on port 3000."
  echo "No process is listening on port 3000."
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It's very useful when running npm start to spin up a React app and you get a Port 3000 is already in use message.

You can also pair it with the npm start command right after it for a better experience. If the port is not in use the script will not do anything.

I went ahead and created an alias for even more convenience, and to do that follow these steps:

  1. Open your .zshrc or .bashrc with: code ~/.zshrc
  2. Add alias killnode=" && npm start"
  3. Run it from you app's folder

Enjoy 🦾

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