Why can't grep group?

Question

linux

Can anyone explain why grep still can't create groups. Often you want to select a unique piece and replace or display only part of it.
An example of getting an ip address (simplified).
It is logical to think like this:
ifconfig | grep '(inet addr\:)(.*)( B') =$2
What you really have to do is:
(ifconfig | grep inet | cut -d: -f2 | awk '{printf $1"\n"}')
Who can explain the reason for the absence of groups in grep?

Answer 1

For starters, you could at least go into man and look at
GREP(1) GREP(1)
NAME
grep, egrep, fgrep - print lines matching a pattern
SYNOPSIS
grep [options] PATTERN [FILE...]
grep [options] [- e PATTERN | -f FILE] [FILE...]
DESCRIPTION
Grep searches the named input FILEs (or standard input if no files are named, or the file name - is given) for lines containing a match to the given PATTERN
. By default, grep prints the matching lines.
In addition, two variant programs egrep and fgrep are available. Egrep is the same as grep -E. Fgrep is the same as grep -F.
It says here that it works with strings, I think that says it all.
Well, if you really don't like doing long pipelines, then learn awk
ifconfig | awk '/inet/{gsub(/.*:/,"",$2);print $2}'