Arithmetic Expansion in Bash: The Little Feature That Makes Your Scripts Cleaner

Summary

If you’ve written Bash for any amount of time, you’ve probably bumped into situations where you needed a quick calculation. Maybe it was a loop counter, maybe file-size math, or maybe you were just trying to add two numbers inside a shell script without summoning half the Unix toolchain. Most of us start with expr, and then eventually escape into awk or bc when things get messy. It works… but it always feels heavier than it needs to be. There’s a simpler tool, always sitting inside the shel...