Best way to simulate “group by” from bash?

Question

Suppose you have a file that contains IP addresses, one address in each line:

10.0.10.1
10.0.10.1
10.0.10.3
10.0.10.2
10.0.10.1

You need a

Answer 1

Solution ( group by like mysql)

grep -ioh "facebook\|xing\|linkedin\|googleplus" access-log.txt | sort | uniq -c | sort -n

Result

3249  googleplus
4211 linkedin
5212 xing
7928 facebook