grep shows occurrences of pattern on a per line basis

Question

From the input file:

I am Peter
I am Mary
I am Peter Peter Peter
I am Peter Peter

I want output to be like this:

1 I am Peter
3 I am Peter Peter Peter
2 I am Peter Peter

Where 1, 3 and 2 are occurrences of "Peter".

I tried this, but the info is not formatted the way I wanted:

grep -o -n Peter inputfile

Answer 1

This is not easily solved with grep, I would suggest moving "two tools up" to awk:

awk '$0 ~ FS { print NF-1, $0 }' FS="Peter" inputfile

Output:

1 I am Peter
3 I am Peter Peter Peter
2 I am Peter Peter

###Edit

To answer a question in the comments:

What if I want case insensitive? and what if I want multiple pattern like "Peter|Mary|Paul", so "I am Peter peter pAul Mary marY John", will yield the count of 5?

If you are using GNU awk, you do it by enabling IGNORECASE and setting the pattern in FS like this:

awk '$0 ~ FS { print NF-1, $0 }' IGNORECASE=1 FS="Peter|Mary|Paul" inputfile

Output:

1 I am Peter
1 I am Mary
3 I am Peter Peter Peter
2 I am Peter Peter
5 I am Peter peter pAul Mary marY John