Remove lines containing space in unix - linux

Question

Below is my comma separated input.txt file, i want to read the columns and write the lines in to the output.txt when any 1 column has a space.
Content of input.txt:
1,Hello,world
2,worl d,hell o
3,h e l l o, world
4,Hello_Hello,World#c#
5,Hello,W orld
Content of output.txt:
1,Hello,world
4,Hello_Hello,World#c#
is't possible to achieve using awk? Please help!

Answer 1

A simple way to filter out lines with spaces is using inverted matching with grep:
grep -v ' ' input.txt
If you must use awk:
awk '!/ /' input.txt
Or perl:
perl -ne '/ / || print' input.txt
Or pure bash:
while read line; do [[ $line == *' '* ]] || echo $line; done < input.txt
# or
while read line; do [[ $line =~ ' ' ]] || echo $line; done < input.txt
UPDATE
To check if let's say field 2 contains space, you could use awk like this:
awk -F, '$2 !~ / /' input.txt
To check if let's say field 2 OR field 3 contains space:
awk -F, '!($2 ~ / / || $3 ~ / /)' input.txt
For your follow-up question in comments
To do the same using sed, I only know these awkward solutions:
# remove lines if 2nd field contains space
sed -e '/^[^,]*,[^,]* /d' input.txt
# remove lines if 2nd or 3rd field contains space
sed -e '/^[^,]*,[^,]* /d' -e '/^[^,]*,[^,]*,[^,]* /d' input.txt
For your 2nd follow-up question in comments
To disregard leading spaces in the 2nd or 3rd fields:
awk -F', *' '!($2 ~ / / || $3 ~ / /)' input.txt
# or perhaps what you really want is this:
awk -F', *' -v OFS=, '!($2 ~ / / || $3 ~ / /) { print $1, $2, $3 }' input.txt

Answer 2

This can also be done easily with sed
sed '/ /d' input.txt

Answer 3

try this one-liner
awk 'NF==1' file
as #jwpat7 pointed out, it won't give correct output if the line has only leading space, then this line, with regex should do, but it has been already posted in janos's answer.
awk '!/ /' file
or
awk -F' *' 'NF==1'

Answer 4

Pure bash for the fun of it...
#!/bin/bash
while read line
do
if [[ ! $line =~ " " ]]
then
echo $line
fi
done < input.txt

Answer 5

columnWithSpace=2
ColumnBef=$(( ${columnWithSpace} - 1 ))
sed '/\([^,]*,\)\{${ColumnBef\}[^ ,]* [^,]*,/ d'
if you know the column directly (by example the 3):
sed '/\([^,]*,\)\{2}[^ ,]* [^,]*,/ d'

Answer 6

If you can trust the input to always have no more than three fields, simply finding a space somewhere after a comma is sufficient.
grep ',.* ' input.txt
If there can be (or usually are) more fields, you can pull that off with grep -E and a suitable ERE, but you are fast approaching the point at which the equivalent Awk solution will be more readable and maintainable.