Matching every instance of a pattern in UNIX

For example I have a string "raghuraghuraghuhello" and I want to display the number of times 'raghu' has occurred in the string. 

We can use the below variant of grep

 echo raghuraghuraghuhello|grep -o raghu|wc -l

hadoop@ubuntu:~$ echo raghuraghuraghuhello|grep -o raghu raghu raghu raghu hadoop@ubuntu:~$ echo raghuraghuraghuhello|grep -o raghu|wc -l 3

Note: When in the first command it just printed out the instances of the pattern, hence we piped it to wc -l