Some pretty usefull git command I never remember :)
Remove all local branches already merged in master
git branch --merged master | xargs -L1 git branch -d
and to keep master out of the result a grep will do
git branch --merged master | grep -v "master" | xargs -L1 git branch -d
update last commit
add your files and run
git commit --amend --no-edit
update last commit message
git commit --amend -m "my new message here"