Git tricks

Update another branch without checking it out

Fast-forward your local master to origin/master while you're on a different branch:

git fetch origin master:master

The same works locally, with . as the "remote". This fast-forwards release to master without leaving your branch (source):

git fetch . master:release

Both refuse if it isn't a fast-forward, so they never create a merge commit or lose work.

Recover lost commits

Commits that no branch points to anymore (after a bad reset, rebase or deleted branch) usually still exist until garbage collection. This lists them with date, subject and author, newest last, so you can find the one you want and git branch rescued <hash> it:

git fsck --full --no-reflogs --unreachable --lost-found | grep commit | cut -d' ' -f3 \
  | xargs -n 1 git log -n 1 --pretty=format:"%ci %s %ae %H"$'\n' | sort

Try git reflog first: it's simpler, and has every commit your branches pointed to recently.