Mass-merge one branch in a Git repository with another branch

merge_all.sh

#!/bin/sh

DEFAULT_PROJECTS="Project_1 Project_2 Project_3"
SOURCE_BRANCH="$1"
DEST_BRANCH="$2"
PROJECTS="$3"

if [[ -z $SOURCE_BRANCH || -z $DEST_BRANCH ]]; then
    echo "Usage: $0 SOURCE_BRANCH DESTINATION_BRANCH"
    exit -1
fi

if [[ -z $PROJECTS ]]; then
    echo "No project specified, merging all projects"
    PROJECTS="$DEFAULT_PROJECTS"
fi

CURRENT_DIR=$PWD

checkout() 
{
    git checkout "$1"
    git pull --rebase
    if [[ $? -ne 0 ]]; then
        echo "** CHECKOUT FAILED - FIX ABOVE ERRORS **"
        exit $?
    fi
}

merge() 
{
    git merge "$1"
    if [[ $? -ne 0 ]]; then
        echo "** MERGE FAILED - FIX ABOVE ERRORS **"
        exit $?
    fi
}

push()
{
    git push origin "$1"
    if [[ $? -ne 0 ]]; then
        echo "** PUSH FAILED - FIX ABOVE ERRORS **"
        exit $?
    fi
}

for PROJECT in $PROJECTS
do
    echo "Merging $PROJECT release $SOURCE_BRANCH into $DEST_BRANCH"
    CURRENT_DIR=$PWD
    cd $PROJECT

    checkout "$SOURCE_BRANCH"

    checkout "master"
    merge "$SOURCE_BRANCH"
    push "master"

    checkout "$DEST_BRANCH"
    merge "master"
    push "$DEST_BRANCH"

    cd $CURRENT_DIR
done