AWK - I need to write a one line shell command that will count all lines that

Question

I need to write this solution as an AWK command. I am stuck on the last question:

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Write a one line shell command that will count all lines in a file called \"f

Answer 1

I think the requirement is very clear

Write a one line shell command that will count all lines in a file called "file.txt" that begin with a decimal number in parenthesis, containing a mix of both upper and lower case letters, and end with a period.

1. begin with a decimal number in parenthesis
2. containing a mix of both upper and lower case letters
3. end with a period

check all three conditions. Note that in 2. it doesn't say "only" so you can have extra class of characters but it should have at least one uppercase and one lowercase character.

The example mixes concepts printing and counting, if part of the exercise it's very poorly worded or perhaps assumes that the counting will be done by wc by a piped output of a filtering script; regardless more attention should have been paid, especially for a student exercise.

Please comment if anything not clear and I'll add more details...