i.e. some stuff and junk about Python, Perl, Matlab, Ruby, Mac X, Linux, Solaris, ...
pdftoppm -png a_pdf_file.pdf img convert *.png a_pdf_file_as_img.pdf
git config --global alias.tree "log --graph --full-history --all --color --pretty=format:\"%x1b[31m%h%x09%x1b[32m%d%x1b[0m%x20%s\""