How to count number of unique values of a field in a tab-delimited text file?

Question

I have a text file with a large amount of data which is tab delimited. I want to have a look at the data such that I can see the unique values in a column. For example,

Answer 1

You can use awk, sort & uniq to do this, for example to list all the unique values in the first column

awk < test.txt '{print $1}' | sort | uniq

As posted elsewhere, if you want to count the number of instances of something you can pipe the unique list into wc -l