title: (Linux AMI) EMR Cluster version of `free` command
body: <p>I'm trying to allocate memory to spark when I start up pyspark from an AWS Linux AMI - ie, pass precise arguments to the <code>driver-memory</code> and <code>executor-memory</code> parameters when I call pyspark.  </p>
  
  <p>I understand I can look here at the <a href="https://aws.amazon.com/ec2/instance-types/" rel="nofollow noreferrer">Instance Types</a> page for the off-the-shelf answer to <em>How much memory do I have on each of this EMR cluster's instances?</em> but I'd like to know if I can do this ("live") from the aws cli itself, so I can see how much I'm actually working with after my bootstrapped spin-up process.</p>
  
  <p>I am also aware of the <code>free</code> command in Linux, but that appears to give me the free memory of only the master node into which I am ssh'd.  I am also aware of the YARN UI and Hadoop APIs, but in this case I'd like to check from the command line, if possible.</p>