git - how to get default branch?

Tested with git 2.9.4 (but possibly works in other versions) in a repo cloned from Github:

$ git symbolic-ref refs/remotes/origin/HEAD | sed 's@^refs/remotes/origin/@@'
master

I found a way to detect the default-branch if it is not master.

git remote show [your_remote] | sed -n '/HEAD branch/s/.*: //p'

I tested it with multiple repo from gitlab, and it worked fine. (for the most situations [your_remote] will be origin, run git remote to check the name of your remote)

git rev-parse --abbrev-ref origin/HEAD will print origin/<default-branch-name>. The git symbolic-ref answers are doing the same thing but need a longer argument.

If the origin repository changes its default branch name, then git remote set-head origin -a will retrieve the new default branch name.