Better support for Darwin/Mac (#17)

Author: huan

README.md

@@ -78,4 +78,15 @@ System                        0                4
 smss.exe                      4                228
 ```
 
+### Mac/Darwin
+
+1. " " need to be striped
+
+```shell
+$ ps -A -o comm,ppid,pid,stat
+COMM              PPID   PID STAT
+/sbin/launchd        0     1 Ss
+/usr/libexec/Use     1    43 Ss
+```
+
 ### LICENSE: MIT

bin/ps-tree.js

@@ -28,6 +28,12 @@ module.exports = function childrenOfPid(pid, callback) {
   // ps              20688 16965 R+
   // ```
   //
+  // Darwin:
+  // $ ps -A -o comm,ppid,pid,stat
+  // COMM              PPID   PID STAT
+  // /sbin/launchd        0     1 Ss
+  // /usr/libexec/Use     1    43 Ss
+  //
   // Win32:
   // 1. wmic PROCESS WHERE ParentProcessId=4604 GET Name,ParentProcessId,ProcessId,Status)
   // 2. The order of head columns is fixed
@@ -96,12 +102,9 @@ module.exports = function childrenOfPid(pid, callback) {
  * @param {string} str Header string to normalize
  */
 function normalizeHeader(str) {
-  if (process.platform !== 'win32') {
-    return str;
-  }
-
   switch (str) {
-    case 'Name':
+    case 'Name':  // for win32
+    case 'COMM':  // for darwin
       return 'COMMAND';
       break;
     case 'ParentProcessId':
@@ -114,6 +117,6 @@ function normalizeHeader(str) {
       return 'STAT';
       break;
     default:
-      throw new Error('Unknown process listing header: ' + str);
+      return str
   }
 }