Bash script to delete all but N files when sorted alphabetically

It’s hard to explain in the title.

I have a bash script that runs daily to backup one folder into a zip file. The zip files are named worldYYYYMMDD.zip with YYYYMMDD being the date of backup. What I want to do is delete all but the 5 most recent backups. Sorting the files alphabetically will list the oldest ones first, so I basically need to delete all but the last 5 files when sorted in alphabetical order.

Answer

The following line should do the trick.

ls -F world*.zip | head -n -5 | xargs -r rm

• ls -F: List the files alphabetically
• head -n -5: Filter out all lines except the last 5
• xargs -r rm: remove each given file. -r: don’t run rm if the input is empty