As with many things in node, child processes can emit an error event. Add a listener for that and you will be able to catch it (no try-catch needed): var spawn = require(‘child_process’).spawn; var child = spawn(‘foo’); child.on(‘error’, function(err) { console.log(‘Oh noez, teh errurz: ‘ + err); });
There is now a power tool that lets you attach to child process: Introducing The Child Process Debugging Power Tool
Use child_process.fork(). It is similar to spawn(), but is used to create entire new instances of V8. Therefore it is specially used for running new instances of Node. If you are just executing a command, then use spawn() or exec(). var fork = require(‘child_process’).fork; var child = fork(‘./script’); Note that when using fork(), by default, … Read more
Using EventEmitter.on(), you attach a full listener, versus when you use EventEmitter.once(), it is a one time listener that will detach after firing once. Listeners that only fire once don’t count towards the max listener count.
Before Node.js 0.7.7, there was only an “exit” event on child processes (and no “close” event). This event would be fired when the child process has exited, and all streams (stdin, stdout, stdout) were closed. In Node 0.7.7, the “close” event was introduced (see commit). The documentation (permalink) currently says: The ‘close’ event is emitted … Read more
You can redirect the program’s stdout to supervisor’s stdout using the following configuration options: stdout_logfile=/dev/fd/1 stdout_logfile_maxbytes=0 Explanation: When a process opens /dev/fd/1 (which is the same as /proc/self/fd/1), the system actually clones file descriptor #1 (stdout) of that process. Using this as stdout_logfile therefore causes supervisord to redirect the program’s stdout to its own stdout. … Read more
Use subprocess: import subprocess #code prog = subprocess.Popen([‘python’, filename, args]) #more code
Use exit event for the child process. var child = require(‘child_process’).exec(‘python celulas.py’) child.stdout.pipe(process.stdout) child.on(‘exit’, function() { process.exit() }) PS: It’s not really a duplicate, since you don’t want to use sync code unless you really really need it.
You can inherit stdin/out/error streams via spawn argument so you don’t need to pipe them manually: var spawn = require(‘child_process’).spawn; spawn(‘ls’, [], { stdio: ‘inherit’ }); Use shell for shell syntax – for bash it’s -c parameter to read script from string: var spawn = require(‘child_process’).spawn; var shellSyntaxCommand = ‘ls -l | grep test | … Read more