Linux Find Week# Of Month

Unfortunately, Linux does not have parameter for Week Number Of Month

I found the solution at https://serverfault.com/questions/383666/how-to-determine-number-of-week-of-the-month

echo $((($(date +%-d)-1)/7+1))

Here is how I have tested.

[oracle@oracle-12201-vagrant ~]$ date -d '20210404'
Sun Apr  4 00:00:00 -05 2021

[oracle@oracle-12201-vagrant ~]$ echo $((($(date -d '20210404' +%-d)-1)/7+1))
1

[oracle@oracle-12201-vagrant ~]$ date -d '20210411'
Sun Apr 11 00:00:00 -05 2021

[oracle@oracle-12201-vagrant ~]$ echo $((($(date -d '20210411' +%-d)-1)/7+1))
2

[oracle@oracle-12201-vagrant ~]$ date -d '20210418'
Sun Apr 18 00:00:00 -05 2021

[oracle@oracle-12201-vagrant ~]$ echo $((($(date -d '20210418' +%-d)-1)/7+1))
3

[oracle@oracle-12201-vagrant ~]$ date -d '20210425'
Sun Apr 25 00:00:00 -05 2021

[oracle@oracle-12201-vagrant ~]$ echo $((($(date -d '20210425' +%-d)-1)/7+1))
4

Why is this even useful?

It can be a continuation of Simplify Log Management For Backup