linux - Shell Command for lines that have decimal number in parenthesis & upper/lower case letters

Question

I have to write a one line shell command that will count all lines beginning with a decimal number in parenthesis, with a mix of both upper and lower case letters, and end with a period.

I'm very confused. I tried some but I cannot get the parenthesis and ending with period part.

Answer 1

The syntax of the parentheses depend on which regex dialect you use.

grep -c '^([0-9]*) [A-Za-z]*.$' file

uses literal parentheses, while

grep -Ec '^([0-9]+) [A-Za-z]+.$' file

needs backslashes. Note also the use of single quotes to prevent the shell from intervening with the arguments.