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Linux / Unix: Shell Remove Empty Lines

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:

Tutorial details
DifficultyEasy (rss)
Root privilegesNo
RequirementsNone
Estimated completion timeN/A
[a] sed command

[b] awk command

[c] perl command

Syntax

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

OR

 
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
 
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{ 3 comments… add one }

  • Roy April 25, 2013, 12:24 am

    You can also use grep :)

    cat output.txt | grep -v “^$” | less

  • Constantine Shulyupin April 25, 2013, 8:14 am
    cat --squeeze-blank

    suppress repeated empty output lines

  • MisaT April 25, 2013, 10:59 am

    I am using grep also, but like this:

    grep . input.txt > output.txt

    There is a dot between grep and input.txt.

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