[Short Tip] Plot live-data in Linux terminal

Recently I realized that one of the disks in my server had died. After the replacement, the RAID sync started – and I quickly had to learn that this was going to take days (!). But I also learned that the time it might take massively jumped up and down.

Thus I thought it would be fun to monitor the progress of this. First, I just crated a command to watch the minutes (calculated into days) every few seconds with watch:

watch 'cat /proc/mdstat |grep recovery|cut -d " " -f 13|cut -d "=" -f 2|cut -d "." -f 1|xargs -n 1 -I {} echo "{}/60/24"|bc'

But since it was jumping so much I was wondering if I could live-plot the data in the terminal (remote server, after all). There are many ways to do that, even gnuplot seems to have an options for that, but I wanted something more simple. Enter: pipeplot

First I tried to use watch together with pipeplot, but it was easier to just write a short for loop around it:

while true;
  cat /proc/mdstat |grep recovery|cut -d " " -f 13|cut -d "=" -f 2|cut -d "." -f 1|xargs -n 1 -I {} echo "{}/60/24"|bc;
  sleep 5;
done \
| pipeplot

And the result is rather nice (also shown in the header image):