CODEWITHSUNDEEP
shellunix
Mufaria Razak
Mufaria Razak

Reputation: 23

Deleting the lines which match the output of another unix command

I have a file as below

cat file
a 1 
a 2
b 3

I want to delete a 1 row and a 2 row as the first column of it is the same.

I tried cat file|uniq -f 1, im getting the desired output. But I want to delete this from the file.

Upvotes: 0

Views: 34

Answers (1)

Kent
Kent

Reputation: 195059

 awk 'NR==FNR{a[$1]++;next}a[$1]==1{print}' file file

This one-liner works for your needs. no matter if your file was sorted or not.

add some explanation:

This one-liner is gonna process the file twice, 1st go record (in a hashtable, key:1st col, value:occurences) the duplicated lines by the 1st column, in the 2nd run, check if the 1st col in the hashtable has value==1, if yes, print. Because those lines are unique lines respect to the col1.

Upvotes: 1

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