Bash 脚本基本呼吸暂停计时器

Question

I am trying to write a bash script that will prompt a user for three variables, and then display a count down type timer so I can perform O2 tables whilst at work on my linux machine (centos6) ,

So far I have a really bad mix of a loop and countdown function written but i am sure that this is a very basic script for someone who comprehends bash scripting,

Essentially I need a variable for a time interval for a breath up (breathing deeply to prepare for a period of apnea) A variable for the first interval of time to hold your breathe Then a variable to increment that hold time by a user provided value as rounds go by,

I would prefer all the variable to be established in seconds only,

Here's an example able of what the end result should be:

this is what i had until i got frustrated with the operation of it

#!/bin/bash

echo "Welcome to the apnea timer, All values should be entered in seconds"
sleep 0.2
read -p "Enter Breath Up Time:" br
read -p "Enter Starting Hold Time Interval:" hold
read -p "Enter Hold Increment Time:" hinc
echo "Starting..." 
sleep 0.5
function cw(){
   date1=$((`date +%s` + $1));   
  while [ "$date1" -ne `date +%s` ]; do   
     echo -ne "$(date -u --date @$(($date1 - `date +%s`)) +%H:%M:%S)\r";  
    sleep 0.1  
  done  

  if [$br -gt 0]
  do 
  cw $br 
  then 
  cw $hold
  then 
  cw $br
  then 
  cw ($hold + $hinc)

Answer 1

Maybe you got frustrated too soon. The hardest part, the countdown function cw , works - you just forgot the closing } after the done line -, only what follows is faulty. So after the done you could write:

}
for set in `seq 8`
do  echo Set $set
    echo Breath
    cw $br 
    echo
    echo Apnea
    cw $hold
    echo
    let hold+=hinc
done