Switch columns in CSV using awk? [duplicate]

Question

I have the exact same question as this one here. Only difference is I have 3 columns only and I am trying to move the 1st column to the end.

The original file looks like this:

col1,col2,col3
2,2015-01-04,23
196,2015-01-20,36

I didn't make the mistake that other questioner did (i.e. not put comma after F or after OFS=). So, my code is

awk -F, '{print $2,$3,$1}' OFS=, old.csv > new.csv

But I am getting the 3rd column (which used to be the first) in a new line:

col1,col2,col3
2015-01-04,23
,2
2015-01-20,36
,196

Why is awk sending the 3rd column data to a new line? I am using awk on Linux Bash Shell (Ubuntu) on Windows, downloaded from here.

Answer 1

It seems like your input file has some additional data in it, such as, DOS style newlines (\r\n), whereas typically on Unix systems, the files only have \n.

For example:

$ cat old.csv
col1,col2,col3
2,2015-01-04,23
196,2015-01-20,36

We can use hexdump to see the actual ASCII of this file:

$ hexdump -C old.csv
00000000  63 6f 6c 31 2c 63 6f 6c  32 2c 63 6f 6c 33 0a 32  |col1,col2,col3.2|
00000010  2c 32 30 31 35 2d 30 31  2d 30 34 2c 32 33 0a 31  |,2015-01-04,23.1|
00000020  39 36 2c 32 30 31 35 2d  30 31 2d 32 30 2c 33 36  |96,2015-01-20,36|
00000030  0a                                                |.|
00000031

Notice the 0a in the HEX output, this is a newline (\n). If I use basically your awk with this file it works as expected:

$ awk -F, '{print $2,$3,$1}' OFS=, old.csv
col2,col3,col1
2015-01-04,23,2
2015-01-20,36,196

If we convert the old.csv file to one that's typically form a Windows/DOS system using a CLI tool unix2dos the modified file, old_dos.csv looks like this:

$ hexdump -C old_dos.csv
00000000  63 6f 6c 31 2c 63 6f 6c  32 2c 63 6f 6c 33 0d 0a  |col1,col2,col3..|
00000010  32 2c 32 30 31 35 2d 30  31 2d 30 34 2c 32 33 0d  |2,2015-01-04,23.|
00000020  0a 31 39 36 2c 32 30 31  35 2d 30 31 2d 32 30 2c  |.196,2015-01-20,|
00000030  33 36 0d 0a                                       |36..|
00000034

Now we see 0d & 0a which is a \r\n. Using awk on this file acts oddly:

$ awk -F, '{print $2,$3,$1}' OFS=, old_dos.csv
,col1col3
,215-01-04,23
,196-01-20,36