Git: delete all branches except a,b,c

git branch | grep -v "a" | grep -v "b" | grep -v "c" | xargs git branch -D

• git branch -- list all available branches.
• grep -v "a" | grep -v "b" | grep -v "c" -- matches all branches except a,b or c.
• xargs git branch -D -- excute git branch -D with the result from grep.