Command line wizardry, part two:

Command line wizardry, part two: Variables and loops in Bash
In our first tutorial on command line wizardry, we covered simple redirection and the basics of sed, awk, and grep. Today, we’re going to introduce the concepts of simple variable substitution and loops—again, with a specific focus on the Bash command line itself, rather than Bash scripting.
—
https://arstechnica.com/gadgets/2021/09/command-line-wizardry-part-two-variables-and-loops-in-bash/?itm_source=parsely-api