Rebase a bunch of branches in a safe(r) way.

catch-up-branches

#!/bin/bash

# Attempt to do the equivalent of:
# massrebase = "!sh -c 'for branch in $@; do git rebase $0 $branch; done;'"

if [[ -z "${SOURCE_BRANCH}" ]] ; then
    SOURCE_BRANCH='origin/master'
fi

# Import some helper functions
. "$(git --exec-path)/git-sh-setup"
require_clean_work_tree 'catch up' 'Please commit or stash any changes.'

function usage {
    echo "$0 branch1 branch2 ..."
    echo "This script will attempt to catch-up the specified branches by:"
    echo "  1. Checking out the branch."
    echo "  2. Rebasing from $SOURCE_BRANCH."
    echo "  3. Repeat as necessary."
    echo "Branches can be globs, like foo*, and will catch-up all matches."
    echo "Optional environment variables:"
    echo "  SOURCE_BRANCH='...'  default: origin/master"
    exit 1
}

if [[ -z "$1" || "$1" = "--help" || "$1" = "help" || "$1" = "-h" || "$1" = "-?" ]] ; then
    usage
fi

REMOTE='origin'
SOURCE="$SOURCE_BRANCH"
RESET=$'\033[0m'
ERR=$'\033[31m'
WARN=$'\033[35m'

if [[ -n $(echo "$SOURCE_BRANCH" | grep '/') ]] ; then
    REMOTE=$(echo "$SOURCE_BRANCH" | cut -d / -f 1)
    SOURCE=$(echo "$SOURCE_BRANCH" | cut -d / -f 2)
fi

git checkout -q "$BRANCH"
git pull -q "$REMOTE" "$BRANCH"

# for each command-line argument ...
while (( "$#" )) ; do
    # list all of the matching branches, as it could be a glob
    BRANCHES=$(git branch --list "$1")
    # for each matching branch
    if [[ -z "$BRANCHES" ]] ; then
        printf "${ERR}No branches matched '$1'.${RESET}\n"
    else
        while read -r TARGET ; do
            if [[ $(echo "$TARGET" | cut -c 1) = '*' ]] ; then
                # Remove the leading * from the current branch
                TARGET=$(echo "$TARGET" | cut -d ' ' -f 2)
            fi
            # One last check to ensure the branch exists
            if [[ -z $(git branch --list "$TARGET") ]] ; then
                printf "${ERR}Branch '$TARGET' does not exist.${RESET}\n"
            else
                MERGE_RESULT=$(git merge-tree `git merge-base "$TARGET" "$SOURCE"` "$SOURCE" "$TARGET")
                if [[ -n $(echo "$MERGE_RESULT" | grep -A3 'changed in both') ]] ; then
                    printf "${ERR}There are conflicts between '$SOURCE' and '$TARGET'${RESET}\n"
                else
                    if [[ -z "$MERGE_RESULT" ]] ; then
                        printf "${WARN}It looks like '$TARGET' is an old, merged branch that could be deleted.${RESET}\n  Remove it with: ${WARN}git branch -d '$TARGET'${RESET}\n"
                    else
                        echo "Catching-up '$TARGET' from '$SOURCE'"
                        git checkout -q "$TARGET"
                        git rebase -q "$SOURCE_BRANCH"
                        git checkout -q "$SOURCE"
                    fi
                fi
            fi
        done <<< "$BRANCHES"
    fi
    shift
done