Rebase a number of branches on top of one another

git-rerebase

#!/bin/sh
# Rebase a number of branches on top of one another
# https://gist.github.com/astyagun/0c9b0ea51ad9dd350c0d7326c364188f
#
# Given
#
#       A---B---C
#      /
#     ----origin/A
#
# and A is tracking a remote branch origin/A
#
# Running
#
#   git checkout C
#   git rerebase A B
#
# will produce
#
#               A'--B'--C'
#              /
#     ----origin/A

GIT_CURRENT_BRANCH=$(git symbolic-ref --short HEAD)

for branch in "$@" "$GIT_CURRENT_BRANCH"; do
  if ! is-valid-git-branch $branch; then
    echo "ERROR: Unrecognized revision or branch: '$branch'!"
    exit 1
  fi
done

PREVIOUS_BRANCH=''

for branch in "$@" "$GIT_CURRENT_BRANCH"; do
  echo
  echo "Switching to branch '$branch'..."
  echo
  if ! git checkout "$branch"; then
    echo
    echo "ERROR: Failed switching to branch '$branch'"
    exit 2
  fi

  if [ "$PREVIOUS_BRANCH" = '' ]; then
    echo
    echo "Rebasing '$branch' on top of it's remote tracked branch..."
    echo
    if ! git rebase; then
      echo
      echo "ERROR: Failed rebasing '$branch' on top of it's remote tracked branch"
      exit 3
    fi
  else
    echo
    echo "Rebasing '$branch' on top of '$PREVIOUS_BRANCH'..."
    echo
    if ! git rebase "$PREVIOUS_BRANCH"; then
      echo
      echo "ERROR: Failed rebasing '$branch' on top of '$PREVIOUS_BRANCH'"
      exit 3
    fi
  fi

  PREVIOUS_BRANCH="$branch"
done