Counting names

[TehOne]

I need to count the ammout of different names that are given by an application in this form:

Name1
Name2
Name3
.......

now I could use:

for online in `$NAMESBIN | tr -d ' '`; do
    USERSON="$( expr "$USERSON" \+ "1" )"
done

however if there was twice John it would get counted as two and not one.

So basically:

John
Britney
David
Paul
John

would result 5 while it's only 4 different names.

How to make it properly ?

[danielsmw]

You'll need to do something to keep track of the names you've already recorded. Depending on how you do this, it could be memory intensive. For example, you could just look back down the list for every name you've counted. You could sort them alphabetically as you go, making it easier to find and verify whether a name has already been used. Or you could use some sort of hash table structure to assign names as keys to some value and then just count the keys.

[TehOne]

Someone has suggesting using sort -u filename | wc -l and then counting but I'd need it done in memory and not file... any ideas?

[burschik]

1. type "man sort"
2. read carefully
3. discover the following statement: "With no FILE, or when FILE is -, read standard input."
4. read Filter (Unix - Wikipedia, the free encyclopedia) or similar