Counting unique values in a column with a shell script

Posted by Lilly Tooner on Stack Overflow See other posts from Stack Overflow or by Lilly Tooner
Published on 2010-05-06T13:31:06Z Indexed on 2010/05/06 13:38 UTC
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bash

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awk

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unique

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values

Hello. I have a tab delimited file with 5 columns and need to retrieve a count of just the number of unique lines from column 2. I would normally do this with Perl/Python but I am forced to use the shell for this one.

I have successfully in the past used *nix uniq function piped to wc but it looks like I am going to have to use awk in here.

Any advice would be greatly appreciated. (I have asked a similar question previously about column checks using awk but this is a little different and I wanted to separate it so if someone in the future has this question this will be here)

Many many thanks!
Lilly

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