Shell倒計時腳本，很完善

#!/bin/bash
#===============================================================
#
#      文件名:countdown.sh
#
#      用途:倒計時
#
#      用法:sh /root/countdown.sh--->不輸入時間默認爲0
#
#      創建時間:2019-09-18
#
#      作者:xxx
#
#==============================================================
read -p "輸入倒計時時間(分鐘):" minute
read -p "輸入倒計時時間(秒鐘):" second

##定義默認值
minute=${minute:-0}
second=${second:-0}

##計算總秒數
second=$[${minute}*60+${second}]

##定義變量
N="\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n"
T="\t\t\t\t\t\t\t"
NT=${N}${T}

##創建顯示函數
function f_print_colour
{
      echo -ne "\033[1;32m$1\033[0m"
}

##倒計時循環
while [ ${second} -gt 0 ]
do
      min=$[${second}/60]
      sec=$[${second}%60]
      let second-=1

      if [ ${min} -lt 10 ];then
         clear
         min=$(printf %02d ${min})
         f_print_colour "${NT}${min}:${sec}"
         if [ ${sec} -lt 10 ];then
            clear
            f_print_colour "${NT}${min}:0${sec}"
         fi
      else
         clear
         if [ ${sec} -lt 10 ];then
            f_print_colour "${NT}${min}:0${sec}"
         fi
      fi
      sleep 1
done

clear
f_print_colour "${NT}00:00"
echo ""

運行的效果，如下圖：