How to remove empty/blank lines from a file in Unix (including spaces)?

linux unix command-line-interface text parsing

426,304

Solution 1

This sed line should do the trick:

sed -i '/^$/d' file.txt

The -i means it will edit the file in-place.

Solution 2

`grep`

Simple solution is by using grep (GNU or BSD) command as below.

Remove blank lines (not including lines with spaces).
```
grep . file.txt
```
Remove completely blank lines (including lines with spaces).
```
grep "\S" file.txt
```

Note: If you get unwanted colors, that means your grep is aliases to grep --color=auto (check by type grep). In that case, you can add --color=none parameter, or just run the command as \grep (which ignores the alias).

`ripgrep`

Similar with ripgrep (suitable for much larger files).

Remove blank lines not including lines with spaces:

rg -N . file.txt

or including lines with spaces:

rg -N "\S" file.txt

Solution 3

sed '/^$/d' file.txt

d is the sed command to delete a line. ^$ is a regular expression matching only a blank line, a line start followed by a line end.

Solution 4

You can use the -v option with grep to remove the matching empty lines.

Like this

grep -Ev "^$" file.txt

Solution 5

Here is an awk solution:

awk NF file.txt

With Awk, NF only set on non-blank lines. When this condition match, Awk default action is to print the whole line.

View more solutions

426,304

Khan

Updated on September 18, 2022

Comments

Khan over 1 year
How do I remove empty/blank (including spaces only) lines in a file in Unix/Linux using the command line?

contents of file.txt
```
Line:Text
1:<blank>
2:AAA
3:<blank>
4:BBB
5:<blank>
6:<space><space><space>CCC
7:<space><space>
8:DDD
```
output desired
```
1:AAA
2:BBB
3:<space><space><space>CCC
4:DDD
```
- Admin about 9 years
  
  For awk, see: Remove blank lines in awk, or using grep, in general, see: How to remove blank lines from a file in shell?
- Admin about 6 years
  
  same question and same answer given over here but with much more votes
- Admin about 5 years
  
  This is an epic answer that pretty much gives every possible solution using grep, sed, awk: stackoverflow.com/questions/16414410/…
MShoubaki about 13 years

It actually needs to be "/^ *$/d" to remove lines that only contain spaces.
kasperd about 8 years

@SeanReifschneider That requirement was not in the question when this answer was written?
mrswadge over 6 years

@SeanReifschneider Would "/^\s*$/d" not be better as it would include tabs? Whilst it's not mentioned in the original post, it seems a stronger option to me.
Trevor Boyd Smith about 6 years

adding the \s* is the same solution given by stackoverflow question
Leo about 6 years

grep . seems to be the simplest solution.
Govind Kailas about 5 years

If you want to skip the commented and blank lines, especially while dealing with conf files use grep -Ev '^#|^$' file.txt
ishandutta2007 about 5 years

I get bad flag in substitute command: 'e'
wisbucky about 5 years

The downside of grep . compared to the other solutions is that it will highlight all the text in red. The other solutions can preserve the original colors. Compare unbuffer apt search foo | grep . to unbuffer apt search foo | grep -v ^$
kenorb about 5 years

@wisbucky You see colors, because grep is aliased to grep --color=auto on your system (check by: type grep). You can run it as \grep or use --color=none parameter.
wisbucky about 5 years

@kenorb If you use grep --color=none ., you will get all white text, which overrides the color formatting of the original command (example: apt search foo)
Jim L. almost 5 years

grep . will match lines containing only spaces, which the OP says is not desired.
kenorb almost 5 years

@JimL. A dot (.) in grep matches any character, so it'll print all non-empty lines. Even the lines with a single empty space are going to be printed.
Jim L. almost 5 years

Yes, and the OP wishes lines containing only spaces to be removed.
kenorb almost 5 years

@JimL. I've improved answer with the solution removing lines with spaces.
kenorb almost 5 years

This command is not compatible with macOS/BSD, secondly it does not produce the same output as OP requested (it produces 5 lines, not 4).
kenorb almost 5 years

This command does not produce the same output as OP requested (it produces 5 lines, not 4).
kenorb almost 5 years

Actually, I think none of the other answers providing what OP requested (exempt Steven one).
kenorb almost 5 years

This produces 6 lines, not 4 as OP requested.
Yet Another User almost 4 years

grep (GNU grep) 3.4 requires -E if you are using @GovindKailas' command