A git alias to delete branches whose remote tracking branches are gone

.gitconfig

# Drop this into your ~/.gitconfig

[alias]
	delete-merged = !bash -c '\
		REMOTE=$1 && \
		REMOTE=${REMOTE:="origin"} && \
		echo "Fetching $REMOTE" && \
		git fetch $REMOTE --prune  && \
		git branch -vv | grep "gone]" | awk \"{ print \\$1 }\" | xargs git branch -d' - 
	
# Run it like so:
# $ git delete-merged origin
#
# If any local branch is tracking a remote branch that has been removed, the local branch will also be removed.
# Note that "origin" is the default parameter, but you can pass your remote name.