Linux / Unix: Shell Remove Empty Lines

Posted on in Categories , , , , last updated April 24, 2013

I am a new Linux user. I have text files with lots of empty lines. How do I delete all empty lines under Linux or Unix operating systems?

You can use any one of the following utility to delete all empty lines from text file:

[a] sed command

[b] awk command

[c] perl command


The syntax is:

command input.txt > output.txt
command [option] input.txt > output.txt
sed '...' input.txt > output.txt
## Gnu/sed
sed -i '...' input.txt 
awk '...' input.txt > output.txt

sed command examples

Type the following sed command to delete all empty files:

sed '/^$/d' input.txt > output.txt
cat output.txt


sed -i '/^$/d' input.txt 
cat input.txt

awk command examples

Type the following awk command to delete all empty files:

awk 'NF > 0' input.txt > output.txt
cat output.txt

perl command examples

Type the following perl one liner to delete all empty files and save orignal file as input.txt.backup:

perl -i.backup -n -e "print if /\S/" input.txt

Verify updated files, type:

cat input.txt
cat input.txt.backup

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

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