12
votes
2answers
505 views

How does awk '!a[$0]++' work?

This one-liner removes duplicate lines from text input without pre-sorting. For example: $ cat >f q w e w r $ awk '!a[$0]++' <f q w e r $ The original code I have found on the internets ...
2
votes
2answers
83 views

Removing lines with a single common field

I have a tab separated file that looks like this: 123 some text 123 some different text 334 some other text 341 more text and I want to do two things. One is to order everything numerically ...
4
votes
3answers
4k views

Get lines with maximum values in the column using awk, uniq and sort

I have a file with next format 2011-12-01 user1 access1 2011-12-01 user1 access2 2011-12-01 user2 access2 2011-12-01 user4 access2 2011-12-02 user1 access1 2012-01-01 user3 access1 2012-01-01 user4 ...