Use a local script before falling back to global commands

A simple zsh function that checks for project-specific wrappers first

Aaron Saray

2026-01-05

I have npm installed globally on my machine. But in some projects, I have a local ./npm script that wraps docker exec to run npm inside a container.

Here's what that looks like in one of my projects:

#!/bin/bash
docker exec -it myproject-node npm "$@"

This is convenient because I can type ./npm run dev and it just works, running inside the container. But sometimes I forget the ./ prefix and accidentally run the global npm instead. Tons of errors and confusion ensue.

What did I do to fix this? If you're using zsh, it's simple: add a function to your ~/.zshrc that checks for a local script first:

npm() {
  if [[ -x ./npm ]]; then
    ./npm "$@"
  else
    command npm "$@"
  fi
}

Now when I type npm run dev, my shell checks if there's an executable ./npm script in the current directory. If so, it runs that. Otherwise, it falls back to the global npm command.

The command keyword is important here. It tells zsh to run the actual npm binary, not our function. Without it, you'd get infinite recursion.

After adding this to your ~/.zshrc, reload it with source ~/.zshrc or just open a new terminal.

Here to help,

Aaron

P.S. Need help modernizing your development workflow or Docker setup? Schedule a call with us.

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