bash countdown

输入 countdown + 秒数，就开始倒计时了

gnu date

function countdown(){  
    local now=$(date +%s)
    local end=$((now + $1))
    while (( now < end )); do   
        printf "%s\r" "$(date -u -d @$((end - now)) +%T)"  
        sleep 0.25  
        now=$(date +%s)
    done  
    echo
}

osx date

function countdown(){  
    echo $2
    local now=$(date +%s)
    local end=$((now + $1))
    while (( now < end )); do   
        printf "%s\r" "$(date -u -j -f %s $((end - now)) +%T)"  
        sleep 0.25  
        now=$(date +%s)
    done
}

参考:https://superuser.com/questions/850368/osx-bash-command-line-countdown-timer?answertab=votes#tab-top