Why is awk not printing out newlines?

Question

I have a file which looks like this:

1 
2
AA 
4
5
AA BB
7
8
AA BB CC
10
11
AA BB CC DD

I am using awk to extract only every nth line where n=3.

>>awk 'NR%3==0' /input/file_foo >> output/file_foobar

The output is appearing in a single line as:

AA AA BB AA BB CC AA BB CC DD

.....and so on

I want it to appear as:

AA 
AA BB 
AA BB CC 
AA BB CC DD 

I tried using \n, printf with \n, and so on but it doesn't work as I expect. Please advise.

Answer 1

A verbose way,

awk '{ if (NR%3==0) { print $0}  }'

Also you can use {printf("%s\n\n", $0)} too. if single \n does not work.

If it still does not work you might need to check the line terminator. It may not be proper. Use the RS variable in awk to separate on the unusual line terminator.

Answer 2

I think the problem is in the way you're showing the data, not in the processing.

$ cat x
1 
2
AA 
4
5
AA BB
7
8
AA BB CC
10
11
AA BB CC DD
$ awk 'NR%3==0' x
AA 
AA BB
AA BB CC
AA BB CC DD
$

I suspect that what you're doing is similar to:

$ awk 'NR%3==0' x > y
$ x=$(<y)
$ echo $x
AA AA BB AA BB CC AA BB CC DD
$ echo "$x"
AA 
AA BB
AA BB CC
AA BB CC DD
$

This would confuse you. See also: Capturing multi-line output to a bash variable.