Unlike sed, the shell is a real programming language
Not long ago a guy wrote a cute little shell script called spark
% spark 1 2 3 4 7 5 3 1 ▂▃▄▅█▆▄▂
Embed it in your prompt or whatever
But its arithmetic was totally broken
It didn't always make the bars the right height
Problem: You need to do fraction arithmetic
The shell doesn't have any
expr uses only integers