exec_tasks_in_bg.sh

_setup() {
    clear
    tput civis
}

_abort() {
    tput cnorm
    exit $status_code
}

_display_help() {
    printf "This script executes an ordered list of command in the background and display a progress bar during the execution\n"
    printf "USAGE:\n"
    printf "\tbash ${name} [tasks]\n"
    printf "EXAMPLE:"
    printf "\n\tbash ${name} 'sleep 1' 'sleep 2' 'exit 1' 'sleep3'\n"
    printf "PARAMETERS:\n"
    printf "\t[tasks]\t\tCommands to run in the background\n"
}

_display_progress_bar() {
    percentage=$(bc <<<"scale=2; (${current_task}/${tasks_number})*100")
    progress=${percentage%%.*}
    progress_bar="\r["
    for (( i=1; i<=$progress_bar_size; i++ )); do

        # The next 4 lines are here to avoid a division by 0
        divider=$((100 / $progress_bar_size))
        if ((divider == 0)); then
            divider=1
        fi
        if ((progress / divider >= i)); then
            progress_bar+="${color}#\e[0m"
        else
            progress_bar+="."
        fi
    done
    progress_bar+="] [${current_task}/${tasks_number}]"
    printf "\033[2;1f$progress_bar"
}

_exec_in_background() {
    _display_progress_bar
    printf "\033[1;1fCurrent task is: \e[1m'${task}'\e[0m"
    SECONDS=0
    eval $task > /dev/null 2>&1 &
    pid=$!
    trap "kill $pid 2> /dev/null" EXIT
    while kill -0 $pid 2>/dev/null; do
        sleep 1
    done
    trap - EXIT
    wait $pid
    status_code=$?
    if [[ "${status_code}" != "0" ]]; then
        color="\e[31m"
    fi
    current_task=$((current_task + 1))
    _display_progress_bar
}

name="${0}"
tasks=( "${@}" )
tasks_number="${#tasks[@]}"
_setup
current_task=0
color="\e[32m"
progress_bar_size=$((COLUMNS / 2))

if ((progress_bar_size == 0)) || ((tasks_number == 0)); then
    _display_help
    status_code=1
    _abort
fi

for task in "${tasks[@]}"; do
    _exec_in_background
    if [[ "${status_code}" != "0" ]]; then
        _abort
    fi
done

_abort