UNIX for Dummies Questions & Answers

Ahh, so first part searchs inside the directory, and second one erases the older directories, if it exceeds more than 1?

main directory (sdcard/backup) contains X subdirectories with files, I want these files to be erased too (I think rm -r does it, doesn't)

Just a note, this is not quite correct (at least on my Debian box here...):
-r deletes everything - when encountering problems, usually -f is added to force deletion.
I remember it was different with non-empty directories on AIX - my Debian box just kills contents of directories... well, you can try it out^^

ls is listing the contents sorted my modification time. Second part, awk is printing all lines but the 1st and calls a system/external command, that's rm.

Edit: It was some permission, must be write permission, that needed the -f to enforce it.

Ok, thanks then, I think it's solved!