gistfile1.txt

sudo gem install git-up
Fetching: colored-1.2.gem (100%)
Successfully installed colored-1.2
Fetching: diff-lcs-1.2.5.gem (100%)
Successfully installed diff-lcs-1.2.5
Fetching: mime-types-1.25.1.gem (100%)
Successfully installed mime-types-1.25.1
Fetching: posix-spawn-0.3.11.gem (100%)
Building native extensions.  This could take a while...
ERROR:  Error installing git-up:
	ERROR: Failed to build gem native extension.

    /usr/bin/ruby2.1 extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h

extconf failed, exit code 1

Gem files will remain installed in /var/lib/gems/2.1.0/gems/posix-spawn-0.3.11 for inspection.
Results logged to /var/lib/gems/2.1.0/extensions/x86_64-linux/2.1.0/posix-spawn-0.3.11/gem_make.out