Hi all, I couldn't help thinking that using that Perderabo script You linked to is way over the top for a simple problem like determining wheher 90-days has passed or not. Actually for any dates after 1970, one should use the date program. One way is to express the date in seconds since 1970-01-01 00:00:00 UTC.
This is eqivalent to "Todays date expressed in seconds, minus the older date, expressed in seconds, and divide the difference by 86400, the number of seconds per day," resulting in the difference in days between the dates. This vaild for any dates after 1970-01-01 up until, well, raher a way up in the future. The date string must for simplicity be expressed in Your current LOCALE.
Now handling dates before 1970, that is a different story!