title: install mongoDB (child process failed, exited with error number 100)
body: <p>I tried to install mongoDB on my macbook air.</p>
  
  <p>I've downloaded zipped file from official website and extract that file and move to root directory.
  After that, under that directory, I've made /data/db and /log folder.</p>
  
  <p>Here is my <code>mongodb.config</code> which describes the basic config for my DB.</p>
  
  <pre><code>dbpath = /mongodb/data/db
  logpath = /mongodb/log/mongo.log
  logappend = true
  #bind ip = 127.0.0.1
  port = 27017
  
  fork = true
  rest = true
  verbose = true
  #auth = true
  #noauth = true
  </code></pre>
  
  <p>Additionally, I want to know what the <code>#</code> means in the config file.</p>
  
  <p>I put this file to <code>/mongodb/bin</code>, <code>/mongodb</code> is the directory I extracted the files into.</p>
  
  <p>I opened terminal and entered <code>./mongod --config mongodb.config</code> and I got this back.</p>
  
  <pre><code>Juneyoung-ui-MacBook-Air:bin juneyoungoh$ ./mongod --config mongodb.config
  about to fork child process, waiting until server is ready for connections.
  forked process: 1775
  all output going to: /mongodb/log/mongo.log
  ERROR: child process failed, exited with error number 100
  </code></pre>
  
  <p>How can I handle this error and what this means? </p>