fork example

forktest.js

var fork = require('child_process').fork;
var spawn = require('child_process').spawn;
var fs = require('fs');
var path = require('path');

function forkProcess() {
  var fd = fs.openSync('/tmp/sensitive_file', 'w');
  var opts = {
  };
  fork(process.argv[1], ["--forked"], opts)
  setInterval(function() {}, 60 * 1000)
};

function spawnProcess() {
  var fd = fs.openSync('/tmp/sensitive_file', 'w');
  var opts = {};

  spawn(process.argv[0], [ process.argv[1], "--forked" ], opts);
  setInterval(function() {}, 60 * 1000)
};

function forked() {
  setInterval(function() {}, 60 * 1000)
}

if (process.argv[2] == '--forked') {
  console.log("forked");
  forked();
} else {
  spawnProcess();
}

gistfile1.sh

jandre@ubuntu:/tmp$ strace -f node forktest.js 2> /tmp/log1 &
[1] 39055

jandre@ubuntu:/tmp$ ps auxw | grep node
jandre   39055  0.1  0.0   4648   820 pts/11   S    19:19   0:00 strace -f node forktest.js
jandre   39056  0.4  0.8 658380  8704 pts/11   Sl   19:19   0:00 node forktest.js
jandre   39058  0.4  0.8 657352  8772 pts/11   Sl   19:19   0:00 node /tmp/forktest.js --forked 

jandre@ubuntu:/tmp$ cat /tmp/log1 | grep sensitive
[pid 39056] open("/tmp/sensitive_file", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 9

#
# both parent and child have the fd /tmp/sensitive_file open
#
jandre@ubuntu:/tmp$ lsof | grep sensitive
node      39056      jandre    9w      REG                8,1        0  827178 /tmp/sensitive_file
node      39058      jandre    9w      REG                8,1        0  827178 /tmp/sensitive_file