Shell script to keep backups for last 3 days, last 3 weeks and last 3 months

Question

Am not entirely sure how to do this due to my lack of shell knowledge.

NOW=$(date +"%Y.%m.%d.%T")

tar czf /backups/web_backup_$NOW.tgz /web/

Can you please assist me to delete old backups so that it only keeps:

1. Last 3 days
2. One backup each from last 3 weeks
3. One backup each for last 3 months

Answer 1

something like this: (just an idea)

mkdir -p monthly
mkdir -p weekly

ln backup_$NOW.tgz weekly/

# find current month
month=$(date +%Y-%m-)
# find the first file of the current month in the weekly folder
first_monthly=$(ls --sort=time -1 weekly/*$month* 2>/dev/null | tail -1)
# and put it in the monthly folder
ln -f $first_monthly monthly/

# we need only 5 weekly backups
ls --sort=time -1 weekly/* 2>/dev/null | tail -n+6 >> /tmp/deletebackups.txt
# we need only 5 monthly backups
ls --sort=time -1 monthly/* 2>/dev/null | tail -n+6 >> /tmp/deletebackups.txt

# delete the extra files
#rm $(cat /tmp/deletebackups.txt) 2>/dev/null
xargs --arg-file /tmp/deletebackups.txt rm

Answer 2

Look at rsnapshot. It might do what you want out of the box.