title: How can I find out if I have Xcode commandline tools installed?
body: <p>I need to use gdb.</p>
  
  <pre><code>ps-MacBook-Air:AcoustoExport pi$ gdb
  -bash: gdb: command not found
  
  ps-MacBook-Air:AcoustoExport pi$ sudo find / -iname "*gdb*"
  Password:
  /usr/local/share/gdb
  /usr/local/Cellar/isl/0.12.1/share/gdb
  :
  </code></pre>
  
  <p>and: </p>
  
  <pre><code>ps-MacBook-Air:AcoustoExport pi$ ls -la /usr/local/share/gdb
  lrwxr-xr-x   1 pi    admin   30 14 Jan 22:01 gdb -&gt; ../Cellar/isl/0.12.1/share/gdb
  </code></pre>
  
  <p>Not quite sure what to make this, clearly it is something installed by homebrew. I don't know why it's there, I don't know whether I could use it instead. It isn't in the search path.</p>
  
  <p>So I figure I need Xcode commandline tools.</p>
  
  <p><a href="https://stackoverflow.com/questions/19907576/xcode-is-not-currently-available-from-the-software-update-server">Xcode is not currently available from the Software Update server</a></p>
  
  <p>^ my current problem exactly.  Comment on that question says "you can get this error if you have them already"</p>
  
  <p>But how do I check whether I have them already?</p>