Replay a range of git commit in another repo (git format-patch + git am with merge commit support)

git-replay.sh

#!/bin/bash

set -eo pipefail

SRC_REPO=""
TARGET_REPO=""
RANGE=""

# generate patches
patch_gen() {
    cd ${SRC_REPO}
    LIST=$(git log --oneline --first-parent --reverse ${RANGE});
    I=0;
    IFS=$'\n';
    for ITEM in ${LIST}; do
        NNNN=$(printf "%04d\n" $I);
        COMMIT=$(echo "${ITEM}" | sed 's|^\([^ ]*\) \(.*\)|\1|');
        TITLE=$(echo "${ITEM}" | sed 's|^\([^ ]*\) \(.*\)|\2|' | sed 's|[ -/~]|-|g' | sed 's|--*|-|g' | sed 's|^\(.\{52\}\).*|\1|');
        FILENAME="${NNNN}-${TITLE}.patch";
        echo "Writing ${FILENAME}...";
        git log -p -c --binary --pretty=email --stat -m --first-parent ${COMMIT}~1..${COMMIT} > ${FILENAME};
        I=$(($I+1));
    done
}

# apply patches
patch_apply() {
    cd ${TARGET_REPO}
    for patch in ${SRC_REPO}/*.patch; do
            echo "== Applying ${patch}..."
            COMMIT_USER=$(head -n 2 $patch | grep 'From: ' | sed 's/From: //' | awk -F" <" '{print $1}')
            COMMIT_EMAIL=$(head -n 2 $patch | grep 'From: ' | sed 's/From: //' | awk -F"<" '{print $2}' | sed 's/>//')
            git -c user.name="${COMMIT_USER}" -c user.email="${COMMIT_EMAIL}" am -3 --keep-cr --committer-date-is-author-date ${patch}
    done
}

patch_gen
patch_apply