git precommit hook which adds big staged files to LFS

precommit.sh

#!/bin/sh
#
# moves big staged files to LFS if not already tracked
#
# the file is tracked as LFS if it is mentioned in .gitattributes
#
#

FILE_SIZE_LIMIT_MB=10

CURRENT_DIR="$(pwd)"

staged_files="$(git diff --cached --name-only | sort | uniq)"

non_staged_files="$(git status --porcelain | grep -v -E '^A\s' | cut -c 1-3 --complement)"
non_staged_files="$(echo "${non_staged_files}" | grep -v "${staged_files}")"

#
# find already tracked files
#
attr=.gitattributes
if [ ! -f $attr ]
then
    echo "create empty $attr"
    touch $attr
    git add -f $attr
fi
already_lfs="$(cut -f1 -d' ' .gitattributes)"

attr_status="$(echo "${non_staged_files}" | grep -E $attr)"

echo "=====> Staged files to commit:"
echo "${staged_files}"
echo

echo "${staged_files}" | while read -r file
do
    if [ ! -f "$file" ]
    then
        continue
    fi

	file_path=$CURRENT_DIR/$file
	file_size=$(ls -l "$file_path" | awk '{print $5}')
	file_size_mb=$((file_size / 1024 / 1024))

    if [ ${file_size_mb} -ge ${FILE_SIZE_LIMIT_MB} ]  # must be lfs
    then

        echo -n "=====> Potentially LFS file ${file} (${file_size_mb} MB): "

        if [ -n "${attr_status}" ]
        then
            echo -e "ERR\n\tmust be tracked as LFS, but .gitattibutes has unstaged changes"
            exit 1
        fi

        if [ -n "$(echo "${already_lfs}" | grep -E "^$file$")" ]
        then
            echo "OK"
        else

            if [ -n "$(echo "${non_staged_files}" | grep -E "^$file$")" ]
            then
                echo -e "ERR\n\tnot tracked as LFS and has unstaged changes"
                exit 1
            else
                echo "moving to LFS..."

                git restore --staged "${file}"
                git lfs track "${file}"
                git add -f "$attr" "${file}"

                echo -e "\tOK"
            fi

        fi
    fi

done

echo "SUCCESSFUL CHECK"