nodeJS child_process.spawn does not work when one of the args has a space in it

Question

nodeJS child_process.spawn does not work when one of the args has a space in it

I am trying to use the child_process.spawn function. The syntax is

child_process.spawn(command, args=[], [options])

Whenever I include a space in any of the elements of the args array, the command simply emits the argument. Here is some code I used to test it

var spawn = require("child_process").spawn

console.log("This works");
var watcher = spawn("ls", ["-l"]);
watcher.stdout.on('data', function(data) {
    process.stdout.write(data.toString());
});

console.log("This does not work");
watcher = spawn("ls", ["-l", "/path with space in it"]);
watcher.stdout.on('data', function(data) {
    process.stdout.write(data.toString());
});

Is this a bug in node? Do I need to escape the space?

Edit: The above code is just an example. Here is the real code. Maybe is has to do with the pipes?

watcher = spawn("supervisor", ["--extensions\ 'coffee|js|css|coffeekup'", "src/app.coffee"]);

javascript
node.js

Answer 1

Don't put spaces in args, just use another argument in the array

var watcher = spawn("supervisor", [
  "--extensions",
  "'coffee|js|css|coffeekup'",
  "src/app.coffee"
]);

A handy little shortcut I found if you want to get quick diagnostic output from your child processes is passing the {stdio: "inherit"} in options

var watcher = spawn("supervisor", [
  "--extensions",
  "'coffee|js|css|coffeekup'",
  "src/app.coffee"
], {stdio: "inherit"});

This way you can see whether everything is working properly right away.

Lastly, depending on where supervisor is installed, you might want to consider using the full path.

var watcher = spawn("/path/to/supervisor", ...);

Answer 2

Yes, you need to escape it, just as you would command line.

watcher = spawn("ls", ["-l", "/path\ with\ space\ in\ it"]);

I doubt it's a bug in node, since you could do something like ['-option="thing with spaces"'] and you shouldn't expect node to guess when to escape spaces and when not to.

ls a\ b/
    blorf

cat a.js
    var spawn = require("child_process").spawn

    watcher = spawn("ls", ["-l", "./a\ b"]);
    watcher.stdout.on('data', function(data) {
        process.stdout.write(data.toString());
    });

node a.js
    total 0
    -rw-r--r--  1 bob  staff  0 Jun  7 17:26 blorf