Making countdown bar with pv

Question

Following this 2013 question, on displaying a countdown in a terminal, I would like to improve the answer a bit using pv to show a progression bar.

Here is my current script.

function countdown {
   date1=$((`date +%s` + $1));
   while [ "$date1" -ge `date +%s` ]; do
     echo -ne "$(date -u --date @$(($date1 - `date +%s`)) +%H:%M:%S)\r";
     sleep 0.1
   done
}

# 7 minutes countdown
countdown $((7*60))

How do I improve this with pv? It looks like it tracks progress measuring data written. In my case I just need to wait and I don't have indicators to measure.

Maybe there are best alternatives as of 2018?

Thanks.

Answer 1

Just do it this way with pv, writing one Byte of character every second.

secs=$((7 * 60))
while [ $secs -gt 0 ]
do 
  echo -n "."
  sleep 1
  : $((secs--))
done | pv -s $secs > /dev/null

echo -n is for

  -n     do not output the trailing newline

pv -s is for

  -s, --size SIZE          set estimated data size to SIZE bytes

sleep 1; : $((secs--)) to decrement the value of $secs every 1 second

Answer 2

You cannot improve this with pv. pv stands for Pipe View, and it tracks the progress of a data flow. Knowing the size and measuring the quantity of data passingh through it, it can give you an estimate of remaining time. If you just need a timer countdown, pv is useless.

You already have something written that can be embellished. Other scripts for your need exists in the web: http://handybashscripts.blogspot.com/2012/01/simple-timer-with-progress-bar.html