Output and count total number of occurrences using grep in linux/nix

Question

I have a data file ( users.dat) with entries like:

user1
user2
user4
user1
user2
user1
user4
...
user3
user2

which command I should ( grep? wc?) use to count how many times each word repeats and output it to user_total.dat like this:

user1 80
user2 35
user3 18
user4 120

the issue is that I cannot specify "user1" or "user19287" because there are too many users with random, but repeating numbers.

But there are repeating users in that DAT file.

Thanks for your help!!!

Answer 1

Use the uniq command to count the repetitions of a line. It requires the input to be sorted, so use sort first.

sort users.dat | uniq -c > user_total.dat

Answer 2

sort <users.dat | uniq -c > user_total.dat

If you want it further in order of occurance pass it through sort a 2nd time using some form the -n argument (read man page on that).

(on edit: bah... didn't realize how dumb the system rendered that bit of code)