title: xxd -r without xxd
body: <p>I'm running on a scaled down version of CentOS 5.5 without many tools available. No xxd, bc, or hd. I can't install any additional utilities, unfortunately. I do have od, dd, awk, and bourne shell (not bash). What I'm trying to do is relatively simple in a normal environment. Basically, I have a number, say 100,000, and I need to store its binary representation in a file. Typically, I'd do something like ...</p>
  
  <pre><code>printf '%x' "100000" | xxd -r -p &gt; file.bin
  </code></pre>
  
  <p>If you view a hex dump of the file, you'd correctly see the number represented as 186A0.</p>
  
  <p>Is there an equivalent I can cobble together using the limited tools I have available? Pretty much everything I've tried stores the ascii values for the digits.</p>