A script to convert all personal GitHub repos' default branch from 'master' to 'main'

master2main.sh

#! /bin/bash

# The script requires jq (https://stedolan.github.io/jq/) and gh-cli (https://cli.github.com/) > 0.10
# It assumes the current user is already logged into their GitHub account, and that they have SSH access set up
# with `gh config set git_protocol ssh`
#
# The script goes over all (up to 100) personal, non-archived, non-forked repositories, that currently has 'master' as
# their default branch and replaces it with NEW_DEFAULT (defined as 'main', but can be easily changed)
#
# It clones a new local repo from each one, creates a NEW_DEFAULT branch in it, pushes it, and also sets it as the
# default branch in GitHub.
# The script *does not* change or update any existing local repos. This will have to be done manually, or with a
# different script.
#
# used samples and tips from https://github.com/cli/cli/issues/1215 (thanks, metcalfc)

NEW_DEFAULT=main

LOGIN=$(gh api graphql -f query='query b{
  viewer {
    login
  }
}' | jq '.data.viewer.login' --raw-output -)

REPOSITORIES=($(gh api graphql -F q='user:${LOGIN} fork:false archived:false' -f query='query($q:String!) {
  repos: search(query: $q, type: REPOSITORY, first: 100) {
    codeCount
    edges {
      node {
        ... on Repository {
          name
          defaultBranchRef {
            name
          }
        }
      }
    }
  }
}' | jq '.data.repos.edges[] | select (.node.defaultBranchRef.name=="master") | .node.name' --raw-output -))

echo "Updating ${#REPOSITORIES[@]} repositories"
for i in "${REPOSITORIES[@]}"; do
  echo "updating ${i}"
  TEMP_FOLDER="temp_${i}"
  gh repo clone $i "${TEMP_FOLDER}" || exit 1
  cd ${TEMP_FOLDER}
  OLD_DEFAULT=$(gh api "repos/:owner/:repo" | jq '.default_branch' --raw-output) || exit 1
  git checkout -b "$NEW_DEFAULT" "origin/${OLD_DEFAULT}" --no-track || exit 1
  git push -u origin "$NEW_DEFAULT" || exit 1
  git REMOTE set-head origin "$NEW_DEFAULT" || exit 1
  gh api -XPATCH "repos/:owner/:repo" -f default_branch="$NEW_DEFAULT" >/dev/null || exit 1
  cd ..
  rm -rf ${TEMP_FOLDER}
  echo "done ${i}"
done