HEAD^ - First parent commit
HEAD~x - xth parent commit
git reset HEAD -- file - Unstage file
git checkout -- file - Revert local changes (checkout file from the current branch)
git checkout branch -- file - Get a file from other branch
git format-patch -1 <SHA> - Make a patch file
git am <file> - Apply a patch file
git checkout-index -a -f --prefix=<destination e.g. /var/www> - Export sources to other folder from local repo (not bare)
git archive --format=tar --remote=ssh://:/<repo_path> master | tar -xf - - Export sources to the current folder (e.g. /var/www/myapp) from remote repo