Concatenate two lines on condition with awk

Question

I'm trying to concatenate two lines when the number of fiels does not match a given number.

Here is an example of input file:

1, z
2
3
4
5, w
6
7

and here is the result I want:

1, z 2
3
4
5, w 6
7

I tried the following code:

awk '
{
   if (NF!=1){
   first=$0
   getline
   print first" ",$0}
   else {print $0}
}' $1

Here is what I obtain:

I don't understand why I get the next line first and then only the second field of the first line.

I add `^M` characters hidden somewhere. I should have known!!! — bosonfute, Dec 12 '14 at 08:57

score 1 · Accepted Answer · answered Dec 02 '14 at 07:19

1

A much more shorter version would be

$ awk 'ORS=NF == 1?"\n":FS' input
1, z 2
3
4
5, w 6
7

ORS is output field separator
FS field separator, which is space by default
NF == 1?"\n":FS' if NF, number of fields equals to 1 then ORS is set to \n else is set to FS

answered Dec 02 '14 at 07:19

nu11p01n73R

Thanks. But it is strange, using your suggestion, I get exactly the same (wrong) output as I mentioned in my question. – bosonfute Dec 02 '14 at 07:21
@bosonfute chances are that your input file may not be correctly formated as in the question. Please do check that – nu11p01n73R Dec 02 '14 at 07:23
@bosonfute I have tested the script in `GNU Awk 3.1.5` it works fine there though :/ – nu11p01n73R Dec 02 '14 at 07:25
Thanks. Weird: I tried on a different VM. All the solutions provided here, including mine that I included in my question, give the correct output. On my own computer, everything gives the wrong output (the one in my question). I don't have a strange distribution: Linux Mint (Debian) and awk version is GNU Awk 4.0.X. On the VM, it is 3.1.7. Maybe awk version is the problem. – bosonfute Dec 02 '14 at 13:50

score 0 · Answer 2 · answered Dec 02 '14 at 07:15

0

Try doing this :

awk 'NF!=1{printf "%s ", $0;next}1' file

Output :

1, z 2
3
4
5, w 6
7

answered Dec 02 '14 at 07:15

Gilles Quénot

score 0 · Answer 3 · answered Dec 02 '14 at 07:15

0

This may do:

awk '{printf "%s%s",$0,(NF>1?FS:RS)}' file
1, z 2
3
4
5, w 6
7

It prints newline if there is one field and else one blank (Field Separator)

answered Dec 02 '14 at 07:15

Jotne

Thanks. But it is strange, using your suggestion, I get exactly the same (wrong) output as I mentioned in my question. – bosonfute Dec 02 '14 at 07:22
@bosonfute Then you indata is different from what you have posted here. PS do not use `getline`. Google `why not use getline` and you see why. – Jotne Dec 02 '14 at 07:24
Thanks. Good to know about getline. I'll be careful now. Still I think my problem is due to awk version, as I mentioned in my reply to nu11p01n73R. – bosonfute Dec 02 '14 at 13:58

3 Answers3