SIGINT is sent twice when pressing Ctrl-C, causing dirty shutdown

I have a package.json with the following scripts:

…
"startemulators": "firebase emulators:start --import seed",
"listen": "onchange 'source_files/*.js' -- touch functions/index.js",
"emulate": "concurrently \"npm run startemulators\" \"npm run listen\""
…

Running the emulate script works as expected, but pressing Ctrl-C to shut the processes down gives me this:

[0] i  emulators: Received SIGINT (Ctrl-C) for the first time. Starting a clean shutdown.
[0] i  emulators: Please wait for a clean shutdown or send the SIGINT (Ctrl-C) signal again to stop right now.
[0] i  emulators: Shutting down emulators.
[0] i  ui: Stopping Emulator UI
[0] ⚠  Emulator UI has exited upon receiving signal: SIGINT
[0] i  functions: Stopping Functions Emulator
[0] i  hosting: Stopping Hosting Emulator
[0] i  database: Stopping Database Emulator
[1] npm run listen exited with code 0
[0]  
[0] ⚠  emulators: Received SIGINT (Ctrl-C) 2 times. You have forced the Emulator Suite to exit without waiting for 3 subprocesses to finish.

So for some reason, a second SIGINT is sent to the firebase command specified in the first script. How come?

[samtstern]

Running into this problem myself, here’s a bit from my package.json:

  "scripts": {
    "build": "tsc",
    "build:watch": "tsc -w",
    "format": "prettier --write src/**/*.ts",
    "emulate": "firebase emulators:start --import=./emulator-data --export-on-exit",
    "serve": "concurrently 'npm run build:watch' 'npm run emulate'"
  },

If I run npm run serve and then press Ctrl+C the Firebase emulators see double SIGINT signals and shutdown without exporting data.

[ghivert]

Hi,

I have the same problem and investigated a little bit. By commenting out that line, I ended up with something working correctly, no double SIGINT, everything is cool.

It looks like spawn-command does not spawn the subprocess in detached mode, and it seems the defaults in concurrently are not setting detached options neither. Because if not, it’s perfectly normal to have the SIGINT sent twice, because it’s received by the subprocess, and then resent with command.kill(signal) a second time.