Code excerpt used in the context of a screencast series entitled "Solving issues with tools running in a shell"

spotting-differences-between-directories-except-for-excluded-files.sh

#!/usr/bin/env bash
set -Eeo pipefail

#	
# ```	
# spot-differences-between-directories "$(pwd)/backup" "$(pwd)/ill-fated-directory"	
# ``` 	
#
function spot-differences-between-directories() {
    local backup_directory
    backup_directory="${1}"

    local target_dir
    target_dir="${2}"

    if [ -z "${backup_directory}" ] || [ ! -d "${backup_directory}" ]; then

        printf 'A %s is expected as %s.%s' 'non-empty string' 'backup directory' $'\n'

        return 1

    fi

    if [ -z "${target_dir}" ] || \
    [ ! -d "${target_dir}" ]; then

        printf 'A %s is expected as %s.%s' 'non-empty string' \
		'directory where files have been deleted' $'\n'

        return 1

    fi

    local output_missing_file
    output_missing_file='file_path='"${target_dir}"'/{} && [ -e ${file_path} ] || echo "${file_path}"'

    (
        cd "${backup_directory}" || exit

        local exclusion_pattern
        exclusion_pattern='.*\(.htacc\|\.xml\|\.md\|docs\|Tests\|node_modules\|vendor\).*'

        find ./ \
            -not -regex "${exclusion_pattern}" \
            -exec bash -c "${output_missing_file}" \;
    )
}
alias spot-differences-between-directories='spot_differences_between_directories'

set +Eeo pipefail