How to repair Homebrew after OS X upgrade

I was getting the following error when running brew after the latest upgrade to OS X (El Capitan).

 /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby: bad interpreter: No such file or directory

I couldn't even run brew update - arg.

This is what I did to correct the issue - git to the rescue!

cd /usr/local/Library

git pull origin master

git pull will throw an error if you have changes in the directory (/usr/local/Library). If so, you'll have to fetch the master branch and perform a hard reset.

git fetch --all

git reset --hard origin/master

You should be able to now use brew again - hurrah!

Note: in the event you installed Homebrew as a non-root user, you'll need to cd to /Users/non-root-user-rname/homebrew/Library instead of /usr/local/Library.

How to restart only the graphical side of OS X via Terminal

I have a variety of mac minis that I use to display stats and system status. Sometimes the Safari browser that is displaying the stats graphs on those remote mac minis locks up / runs out of memory. This makes using Remote Desktop to restart the remote Safari session impossible as I can't login to the machine. Rather than walk over to force a reboot I can ssh into the box and restart the WindowsServer (WindowsServer is the graphical user interface manager and is typically the thing that is borked). 

To resolve this issue I ssh into the machine via Terminal and then run the following command:

sudo killall -HUP WindowServer

Any open applications will be forced to close so use the command with caution.

How to unpack a .deb file on Mac OS X without installing it

If you use Xcode, a utility called ar is installed. You can run the following command:

ar -x path/to/filename.deb

If you don't use Xcode, you could also install ar using Homebrew and run the same command.

Alternatively, you could use Homebrew to install the dpkg utility which has many more options to work against .deb files.

dpkg -c path/to/filename.deb