How to find empty lines in files in Linux

In Linux, how to find an empty line in a file and output an empty line number.


Recently, such problems have been encountered in processing data analysis.

This article will show you how I use Linux commands to find empty lines in a file.

There are three common ways to find empty lines in a file, using the grep and awk commands.

Method 1

In the following method, we use the grep command and regular expression to find empty lines in the file.

➜  ~ grep -n -e "^$" test.log

Explain:

n, indicating the number of output lines (starting from 1)

e, indicating specify a pattern used during the search of the input

^, indicating the beginning

$, indicating the end

Method 2 &Method 3

In the following two methods, we use the if conditional judgment expression of the awk command to find empty lines in the file.

➜  ~ awk '{if($0 == "") {print NR}}' test.log

➜  ~ awk '{if(!NF) {print NR}}' test.log

Explain:

Awk NR variable, which indicates the serial number of the current record. It is the line number when processing a single file.

Awk NF variable, indicating the number of fields in the current record.

Awk $0 variable, indicating the current sequence number value.

OK. The above is the method I use to find empty lines in the file.

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