Shell Scripting / Bash Tricks

Stop writing endless loops just to rename a bunch of files

🧩 The Challenge

Renaming a hundred files based on a specific pattern used to be a nightmare of nested loops and substring manipulation. I spent way too many nights writing brittle scripts that would inevitably fail because a filename had a space or a weird special character.

💡 The Fix

There is a built-in rename utility that uses Perl-compatible regular expressions to handle bulk renames in one shot. It’s safer, faster, and keeps you from having to debug a messy for-loop.

rename 's/\.old_extension$/.new_extension/' *.old_extension

⚙️ Why It Works

This utility essentially runs a global find-and-replace across the entire argument list using standard regex patterns. Since it’s built on Perl, it handles complex patterns and captured groups far better than a standard shell globbing approach.

🚀 Pro-Tip: Always run it with -n first so you can see what will happen before you accidentally rename your entire production directory.

Linux Tips & Tricks | © ngelinux.com | 9/4/2026