To rename all `.txt` files in the current working directory (CWD) to `.md` using Bash, you can use the `rename` command or a `for` loop. Here's how you can do it: Using the `rename` command: ```bash rename 's/\.txt$/.md/' *.txt ``` This command uses regular expressions to match the `.txt` extension at the end of the file names and replaces it with `.md`. Using a `for` loop: ```bash for file in *.txt; do mv -- "$file" "${file%.txt}.md" done ``` This loop iterates over all `.txt` files in the current directory, and for each file, it uses the `mv` command to rename it by removing the `.txt` extension and appending `.md` instead. Both methods achieve the same result of renaming all `.txt` files in the CWD to `.md`. Choose the one that suits your preference or the tools available in your system.