Delete stale files by last accessed time and created time

I implemented file based caching on one of my projects to cache large number of responses which are CPU and memory intensive. The file caching worked as a charm at start but soon I started to hit the storage capacity of the web server. So I wanted a script that can be configured in cron job which then can checks the configured directory in regular intervals to see whether the directory has reached a defined threshold. If so then delete stale files that are no more in use.

My algorithm flow:

Check whether the directory reached threshold.
If reached then start deleting files that are not accessed in last 30 days.
If still the threshold is not reached then decrement access time by 10 days and proceed deleting those files. ( This recursive loop goes on till the access time reaches a configured minimum limit. I don't want to delete all the caches files that are recently being accessed).
If still the threshold is not reached then start deleting the oldest created files starting from 30 days and decrementing by 10 days till a pre configured minimum limit is reached.
If still the threshold is not reached then email a notification to a configured email address.

Implementation

The following script is designed to be run either manually or can be configured as a cron job to monitor a specific directory. The script takes 2 arguments.

Directory path.
Threshold limit ( in MB)

Usage:

  $./file_cache_clean.sh [directory_path] [threshold_limit_in_mb]

Optional Step: Set up your crontab

To make this run every 12 hours, I added this to my crontab (using crontab -e):

0 0,12 * * * /home/user/scripts/file_cache_clean.sh /var/files/cache 1000