title: Meaning of tilde in Linux bash (not home directory)
body: <p>First off, I know that <code>~/</code> is the home directory. CDing to <code>~</code> or <code>~/</code> takes me to the home directory.</p>
  
  <p>However, <code>cd ~X</code> takes me to a special place, where <code>X</code> seems to be anything.</p>
  
  <p>In bash, if I hit "<code>cd ~</code>" and hit tab, it shows a bunch of possible <code>~X</code> options like <code>~mail</code> and <code>~postgres</code> and <code>~ssh</code>.  Going to those folders and doing a <code>pwd</code> shows me that these folders are not in the home directory; they're all over the place.</p>
  
  <p>They are not aliases. I've checked. 
  They're not <code>env.</code> variables, or else they'd require a <code>$</code>.</p>
  
  <p>What is setting these links, and where can I find where these are being set?</p>