Allow passing mitiple pids

README.md

@@ -51,6 +51,14 @@ psTree(child.pid, function (err, children) {
 });
 ```
 
+You can also pass more then one pid in array, and get corresponding array as result
+``` js
+psTree([child1.pid, child2.pid], function (err, children) {
+  cp.spawn('kill', ['-9'].concat(children[0].map(function (p) { return p.PID })));
+  cp.spawn('kill', ['-9'].concat(children[1].map(function (p) { return p.PID })));
+}); 
+```
+
 If you prefer to run **psTree** from the command line, use: `node ./bin/ps-tree.js`
 
 ## Cross Platform support

index.js

@@ -1,18 +1,18 @@
 'use strict';
 
 var spawn = require('child_process').spawn,
-    es    = require('event-stream');
+  es = require('event-stream');
 
 module.exports = function childrenOfPid(pid, callback) {
   var headers = null;
 
   if (typeof callback !== 'function') {
     throw new Error('childrenOfPid(pid, callback) expects callback');
   }
-
-  if (typeof pid === 'number') {
-    pid = pid.toString();
-  }
+  
+  var pidIsArray = Array.isArray(pid)
+  var pids = pidIsArray ? pid : [pid]    
+  pids = pids.map(pid => pid.toString());
 
   //
   // The `ps-tree` module behaves differently on *nix vs. Windows
@@ -73,17 +73,20 @@ module.exports = function childrenOfPid(pid, callback) {
       return cb(null, row);
     }),
     es.writeArray(function (err, ps) {
-      var parents = [pid],
+      var results = pids.map(function (pid) {
+        var parents = [pid],
           children = [];
 
-      ps.forEach(function (proc) {
-        if (parents.indexOf(proc.PPID) !== -1) {
-          parents.push(proc.PID)
-          children.push(proc)
-        }
-      });
+        ps.forEach(function (proc) {
+          if (parents.indexOf(proc.PPID) !== -1) {
+            parents.push(proc.PID)
+            children.push(proc)
+          }
+        });
+        return children
+      })
 
-      callback(null, children);
+      callback(null, pidIsArray ? results : results[0]);
     })
   ).on('error', callback)
 }

test/test.js

@@ -38,6 +38,34 @@ test(cyan('Spawn a Parent process which has a Two Child Processes'), function (t
   // need more time on a slow(or heavy load server). maybe promise.then is better instead of the timeout
 });
 
+test(cyan('Spawn Two parent processes each has a Two Child Processes'), function (t) {
+  var parent1 = cp.exec('node ' + scripts.parent, function (error, stdout, stderr) {});
+  var parent2 = cp.exec('node ' + scripts.parent, function (error, stdout, stderr) {});
+
+  setTimeout(function () {
+    psTree([parent1.pid, parent2.pid], function (err, children) {
+      if (err) { console.log(err); }
+      console.log(red('Children: '), children, '\n');
+      t.true(children[0].length > 0, green('✓ There are ' + children[0].length + ' active child processes of first'));
+      t.true(children[1].length > 0, green('✓ There are ' + children[1].length + ' active child processes of second'));
+      treeKill(parent1.pid);
+      treeKill(parent2.pid);
+    });
+
+    setTimeout(function () {
+      psTree([parent1.pid, parent2.pid], function (err, children) {
+        if (err) { console.log(err); }
+        // console.log('Children: ', children, '\n');
+        // console.log(' ')
+        t.equal(children[0].length, 0, green('✓ No more active child processes of first(we killed them)'));
+        t.equal(children[1].length, 0, green('✓ No more active child processes of second (we killed them)'));
+        t.end();
+      });
+    }, 2000); // give psTree time to kill the processes
+  }, 500); // give the child process time to spawn
+  // need more time on a slow(or heavy load server). maybe promise.then is better instead of the timeout
+});
+
 test(cyan('FORCE ERROR by calling psTree without supplying a Callback'), function (t) {
   var errmsg = 'Error: childrenOfPid(pid, callback) expects callback'
   // Attempt to call psTree without a callback