Export branch from git repository and preserve existing file listed in variable or .gitattributes

git-export.sh

#!/bin/bash

REPO="[email protected]:lgelo/demo.git"
BRANCH="master"
TARGET="/srv/app/demo"
PRESERVE=( settings.py )

STAGING=$(mktemp -d)
CWD=${PWD}

git clone --depth 1 --branch ${BRANCH} ${REPO} ${STAGING}

if [ -f .gitattributes ]; then
        mapfile -O ${#PRESERVE[@]} -t PRESERVE < <(grep export-ignore .gitattributes | awk '{print $1}')
fi

if [ ! -d "${TARGET}" ]; then
        mkdir -p "${TARGET}"
fi

if [ -n "${PRESERVE}" ]; then
        printf -v exclude "%s|" "${PRESERVE[@]}"
        exclude=${exclude%?}
        printf -v exclude "!(%s)" "${exclude}"
        shopt -s extglob
        rm -rf ${TARGET}/${exclude}
else
        rm -rf ${TARGET}/*
fi

cd ${STAGING}
git archive ${BRANCH} ${STAGING} | tar -x -C ${TARGET}
cd ${CWD}
rm -rf ${STAGING}