Delimiter is being changed with fields

Question

I have a file with values organized in columns, and separated by commas, as in the file below:

324,01,1,113333600000,1,,
016,01,1,134954200000,1,,
770,01,1,109069200000,1,,
853,01,1,111518800000,1,,

When I use the following awk command, the delimiter is being changed from commas to spaces

Code:

awk -F, '{$4=$4/1024}{print $0}'

The output becomes:

324 01 1 110677343.75 1  
016 01 1 131791210.93 1  
770 01 1 106512890.62 1  
853 01 1 108905078.12 1 

How can I change the value of the field without changing the delimiter?

Answer 1

Set OFS as well:

awk -F, -v OFS=, '{$4=$4/1024}1'

The OFS determines how output fields are delimited. If you don't set it, the default is a space.

Answer 2

muru answer is correct, but I prefer using the BEGIN block for this task:

awk 'BEGIN{FS=OFS=","}{$4=$4/1024}1'

Answer 3

There is a problem with the given answers in gawk:

If no field was changed on the record, setting OFS may get ignored.

Putting the following line inside your record processing will solve this:

$1=$1;

A complete example to change the separator to ";" would be:

</etc/passwd awk -F: -v OFS=; '{$1=$1; print}'