Sort Contents by File Extension

ls -X

The name of a file is not the only thing you can use for alphabetical sorting. You can also sort alphabetically by the file extension. In other words, you can tell ls to group all the files ending with .doc together, followed by files ending with .jpg, and finally finishing with files ending with .txt. Use the -X option (or --sort=extension); if you want to reverse the sort, add the -r option (or --reverse).