[snakes1100]

-f, --file=ARCHIVE - this is telling it to use the file/archive name you are giving in the command, so how does that not make sense to you marco?

-p - it doesnt matter if you use it while compressing or uncompressing, it just preserves the ownership/permissions and will do no harm if its there while compressing

if you want to delete backups older than 5/10/15/20/25/30 days, you can simply use this in your cron job, simply change the number after the + in the command below.

cd /$backupdir

find /$backupdir -atime +30 -exec rm -rf {} \;

You can place that that the end of your cron file for backups