title: Which characters are allowed in a bash alias
body: <p>I recently added </p>
  
  <pre><code>alias ..='cd ..'
  alias ...='cd ../..'
  alias ....='cd ../../..'
  </code></pre>
  
  <p>to my bash_aliases file. Playing around with this, I noticed that while aliasing <code>..</code> was allowed, aliasing <code>.</code> was not. What other punctuation characters are allowed in bash aliases?</p>