grep -v

grep has various options. I frequently use -v option to filter lines without the keyword.

grep -v human data.txt

where data.txt is a bunch of data to be greped. We can filter out lines with keyword human.

Other example is to filter the lines which have a value in the first column. When the first column is missing, head of the line is '\t' (tab character) in the tab-deliminated text. We can make use of grep -v command below to filter out the lines without the first column.

grep -v ^$'\t' data.txt

^ means the head of line, and $'\t' means tab character. It greatly enhances the efficiecy of our study to have a list of lines with required data.

Written by bonohu in shell on 金 19 4月 2019.