Preparing screencast gifs on OS XEdit
Installation
$ brew cask install xquartz
$ open /opt/homebrew-cask/Caskroom/xquartz/2.7.7/XQuartz.pkg
$ brew install ffmpeg imagemagick gifsicle
$ sudo gem install screengif
Use
$ brew cask install xquartz
$ open /opt/homebrew-cask/Caskroom/xquartz/2.7.7/XQuartz.pkg
$ brew install ffmpeg imagemagick gifsicle
$ sudo gem install screengif
After recording a movie with, say, QuickTime Player:
$ screengif -i Untitled.mov -o bug-repord.gif
OS upgrades
I found when upgrading to OS X El Capitan that I had to reinstall, because screengif was somewho trying to use an old version of ImageMagick. So I just uninstalled and reinstalled everything:
$ brew cask uninstall xquartz
$ brew uninstall --force ffmpeg imagemagick gifsicle
$ sudo gem uninstall screengif rmagick
On upgrading to Sierra I found that things had changed again, and the answer lied in this Stack Overflow post:
$ sudo gem uninstall rmagick screengif
$ brew uninstall --force ffmpeg imagemagick gifsicle
$ brew install ffmpeg imagemagick gifsicle
$ brew install imagemagick@6
$ brew unlink imagemagick
$ brew link --force imagemagick@6
$ export PKG_CONFIG_PATH="/usr/local/opt/imagemagick@6/lib/pkgconfig:$PKG_CONFIG_PATH"
$ sudo gem install screengif
In short, a world of pain, and some voodoo coding until I found what worked.