EMFILE error during directory monitoring in nodemon

Answer

Yes – nodemon lets you exclude directories that generate many file‑watch events, so you don’t have to rely solely on the --legacy-watch polling mode.

Confirmed facts

• nodemon uses chokidar (or Node’s fs.watch) which consumes one file descriptor per watched file or directory.
• When the per‑process limit (shown by ulimit -n) is exceeded, the OS returns EMFILE.
• Adding ignore patterns reduces the number of watched entries; raising the limit allows more descriptors.

Steps to resolve the EMFILE error

1. Check the current descriptor limit:

   ulimit -n

   (on Linux/macOS) or the equivalent fs.nr_open on your system.
2. Add ignore patterns for high‑volume folders. You can do this either on the command line or in a nodemon.json file:

   nodemon --ignore "node_modules/**" --ignore "build/**" --ignore "dist/**" your-app.js

   or in nodemon.json:

   {
     "ignore": ["node_modules/**", "build/**", "dist/**"]
   }

3. Restart nodemon and verify that the EMFILE message disappears from the startup log.
4. If the error persists, increase the limit before launching nodemon, for example:

   ulimit -n 4096 && nodemon your-app.js

   (choose a value safely above the current usage but not excessively high).
5. As a last resort, switch to the polling‑based watcher:

   nodemon --legacy-watch your-app.js

   This avoids native descriptors but may increase CPU usage and latency.

Please provide the output of ulimit -n (or the equivalent limit on your system) so we can tell whether raising the limit is necessary or if the ignore patterns alone will suffice.