How do I remove blank lines from files?

Question

I have a file (hosts) with some lines without content, how do I remove that lines without content?

Maythux · Accepted Answer · 2015-06-12T15:46:56.023

13

Using sed

Type the following command:

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

Using grep

Type the following command:

grep -v '^$' input.txt > output.txt

edited Jun 12 '15 at 15:46

answered Jun 12 '15 at 15:27

Maythux

84,289

terdon · Answer 2 · 2015-06-12T17:35:09.210

8

Many ways:

Use sed and edit the file in place.
```
sudo sed -i -rn '/\S/p' /etc/hosts
```

Same, but with Perl:

sudo perl -i -ne 'print if /\S/' /etc/hosts

Newer versions of GNU awk, in place again:
```
sudo awk -i inplace '/\S/' file
```

All of the above solutions will also remove lines that contain nothing but whitespace. If you only want to remove empty lines, and leave lines that contain spaces or tabs etc, change the /\S/ to /^$/ in all of the above examples.

edited Jun 12 '15 at 17:35

answered Jun 12 '15 at 15:33

terdon

100,812

for the sake of completeness, you can also say grep -v '.' file. – fedorqui Jun 12 '15 at 19:04
1

@fedorqui indeed, but I think you meant grep '.' file, we want to remove empty lines, not keep them. – terdon Jun 12 '15 at 19:26
+1, however the -r switch on the sed command is not really needed there since you're not taking advantage of ERE-specific syntax – kos Jun 13 '15 at 08:12

mchid · Answer 3 · 2022-02-17T20:41:29.320

1

Sometimes the other commands will fail to remove blank lines if the lines contain a blank space. The following will remove all blank lines including lines that contain only blank spaces.

grep -v '^[[:space:]]*$' input.txt > output.txt

edited Feb 17 '22 at 20:41

answered Feb 17 '22 at 20:29

mchid

43,546
8
97
150

Is a nice solutions, in xml files for example is possible to have spaces. A similar solution with sed can be: "sed '/^\s*$/d' input.txt > output.txt" – TheGabiRod Nov 16 '22 at 19:58

score 0 · Answer 4 · answered Jan 27 '22 at 05:44

You can do this in the default Ubuntu Text Editor (gedit) by:

Press Ctrl+H to open Find and Replace
In the 'Find' box, enter \n\n which signifies two new lines without text in-between them.
In the 'Replace' box, enter \n
Click 'Replace All'

If the text file was produced in windows, you may want to try \r\n.

score 0 · Answer 5 · answered Apr 16 '16 at 19:18

0

You can use Vim in Ex mode:

ex -sc v/./d -cx hosts

/./ find non blank lines
v invert selection
d delete
x save and close

answered Apr 16 '16 at 19:18

Zombo

1

How do I remove blank lines from files?

5 Answers5

Using sed

Using grep