using grep and egrep in the terminal
 

Create a file containing some lines that you think would match
the regular expression: (^[09]{1,5}[azAz]+$)|none and some
lines that you think would not match.
Use egrep to see if your
intuition is correct.

Hi,

This screams: Homework! Which we don't do for you (because I don't want to and because the LQ rules say so). Get to the chapter that deals with regular expressions, read the (e)grep man page.

If you get stuck on a specific issue, you can post it here and we can give you some pointers.

This looks like your second "cut and paste" homework question.

There is a lot of misunderstanding about homework here. You ARE allowed to post homework questions. The rules only say that you should not expect us to actually do anything.

My rule: If you just cut and paste from the assignment sheet---and give no evidence of trying to solve the problem--I will not lift a finger to help you.

As a minimum, tell us what text they use in the class and where you are getting stuck.

OK

I've done the exercise and it behaved pretty much as I expected:D

All the information you need is included in the question you posted. Cross reference your homework with the following:
BTW there are 186 unique combinations that match the regular expression (^[09]{1,5}[azAz]+$)
There are 248 unique combinations if (as I suspect) the regular expression should have been (^[09]{1,5}[azAZ]+$)