git-get-default-branch

#!/usr/bin/env bash
# Author: github.com/danielhoherd
# License: MIT
# Purpose: for each remote, print: <name of remote> <default branch>
# EG:   $ git-get-default-branch
#       origin master
#       github gh-pages
#
# If the repo default branch has been renamed, you must update it by running something like:
#       git remote | xargs -r -I {} git remote set-head {} -a
#
# If you just want to check out the default branch really quickly:
#       git checkout $(git branch -r | awk -F/ '/HEAD/ {print $NF}')
#
# Or if you want an alias to check out the default branch quickly::
#       git config --global alias.co-default '!'"git checkout \$(git branch -r | awk -F/ '/HEAD/ {print \$NF}')"


if [[ "${#@}" -gt 0 ]] ; then
  remotes=( "${@}" )
else
  # In 2023, macOS 13 still has bash 3.2.57, which was released in 2014 🙄
  if [[ "${BASH_VERSINFO[0]}" -lt 4 ]] ; then
    remotes=()
    while IFS='' read -r line ; do
      remotes+=("$line")
    done < <(git remote)
  else
    mapfile -t remotes < <(git remote)
  fi
fi

for remote in "${remotes[@]}" ; do
  git remote set-head "$remote" -a >/dev/null
  branch=$(git ls-remote --symref "$remote" HEAD | awk '$2 ~ /^refs/ { sub(".*/","", $2) ; print $2 }')
  echo "$remote $branch"
done