Homebrew: List packages and what uses them

For anyone that uses Homebrew a lot, its very easy to amasse many casks (installed packaged) and never quite know which ones are still needed. I did some googling and found a really interesting blog post by Mark H. Nichols about listing all brew dependencies.

I then decided to invert that logic; to list all my casks, with each one showing what uses it. Anything that has nothing using it is either an oprhaned cask or is something "standalone" which is not installed as a dependency on something else.

NOTE: The script from Mark's website uses zsh; I do not have that, I use plain old Bash. It is still possible to get colours though!

brew list -1 | while read cask; do echo -ne "\x1B[1;34m $cask \x1B[0m"; brew uses $cask --installed | awk '{printf(" %s ", $0)}'; echo ""; done

And some example output:

 atk  gtk+  pygtk 
 autoconf  automake  php54-apc  php54-mcrypt  php54-memcache  php54-tidy  tsocks 
 cairo  gtk+  harfbuzz  pango  py2cairo 
 cmake  percona-server55 

And a screenshot: