I had a container with a DB crap itself yesterday so I'm trying to speed up my learning to back up stuff.
I came across a script that taught me how to back-up a containerized postgres db at given intervals and it works. I managed to create db dumps and restore them. I've documented everything and now my whole docker-compose/env etc are on git control.
There's one part of the script I don't decypher but I'd like to maybe change it. It is about the number of back-up copies.
Here's the line from the tutorial:
ls -1 /backup/*.dump | head -n -2 | xargs rm -f
Can someone explain to me what this line does?
I'd like to keep maybe 3 copies just in case the auto-backup backs up a rotten one.
The first command (ls -1 /backup/*.dump) just creates a list of files in the backup folder that have the extension .dump. the output of the prior command is then sent to the next command (head -n -2) this cuts the list down to everything except the last 2 items in the list this is then sent to the final command which takes the list and runs the final (rm -f) command with the items in the list as the targets to delete.
There is an explanation on that post that explains it in better detail but in simple terms it deletes all files but the most recent 3 files in the directory that have the .dump extension