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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
This sed line should do the trick:
sed -i '/^$/d' file.txt
The -i means it will edit the file in-place.
\s* is the same solution given by stackoverflow question
Feb 21, 2018 at 19:17
grepSimple solution is by using grep (GNU or BSD) command as below.
Remove blank lines (not including lines with spaces).
grep . file.txt
Remove completely blank lines (including lines with spaces).
grep "\S" file.txt
Note: If you get unwanted colors, that means your grep is aliases to grep --color=auto (check by type grep). In that case, you can add --color=none parameter, or just run the command as \grep (which ignores the alias).
ripgrepSimilar with ripgrep (suitable for much larger files).
Remove blank lines not including lines with spaces:
rg -N . file.txt
or including lines with spaces:
rg -N "\S" file.txt
See also:
grep . compared to the other solutions is that it will highlight all the text in red. The other solutions can preserve the original colors. Compare unbuffer apt search foo | grep . to unbuffer apt search foo | grep -v ^$
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.
grep --color=none ., you will get all white text, which overrides the color formatting of the original command (example: apt search foo)
grep . will match lines containing only spaces, which the OP says is not desired.
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.
You can use the -v option with grep to remove the matching empty lines.
Like this
grep -Ev "^$" file.txt
-E, at least not with GNU grep, but apart from that I'm so pleased to see this done with grep! It's what I reach for in preference to sed, every time; in-line filters seem to me to be better than in-line editors.
Mar 28, 2011 at 22:45
grep -Ev '^#|^$' file.txt
Mar 7, 2019 at 4:11
grep (GNU grep) 3.4 requires -E if you are using @GovindKailas' command
Aug 15, 2020 at 4:07
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.
To remove empty lines, you could squeeze new line repeats with tr:
cat file.txt | tr -s '\n' '\n'
Here is the method using ex editor (part of Vim):
ex -s +'v/\S/d' -cwq test.txt
For multiple files (edit in-place):
ex -s +'bufdo!v/\S/d' -cxa *.txt
Note: The :bufdo command is not POSIX.
Without modifying the file (just print on the standard output):
cat test.txt | ex -s +'v/\S/d' +%p +q! /dev/stdin
For me @martigin-heemels command was throwing error this fixed it (ie a dummy param to i),
sed -i '' '/^$/d' file.txt
xargs if you dont mind stripping leading whitespace
$ docker run -it --rm alpine sh
/ # cat <<eof > /tmp/file
> one
>
> two
> three
>
>
> four
> eof
/ # cat /tmp/file
one
two
three
four
/ # cat /tmp/file | xargs -n1
one
two
three
four
