How to make awk gsub return a tab-separated line?

Question

I use awk gsub to replace a string in a specific column of my tab-separated file:

cat test.txt 
1   1   2032    1
2   1   2032    2
3   1   999 3
4   1   2032    4
5   1   9999    5

However, the modified line is separated by spaces, even if -F "\t" was specified:

awk -F "\t" '{gsub(/^999$/,"XXX",$3);print}' test.txt
1   1   2032    1
2   1   2032    2
3 1 XXX 3
4   1   2032    4
5   1   9999    5

How can I have the modified line(s) separated by tabs as well ?

Answer 1

You should set

OFS="\t"

so :

awk -F "\t" '{gsub(/^999$/, "XXX", $3); print}' OFS="\t" test.txt

or

awk -F "\t" -v OFS="\t" '{gsub(/^999$/, "XXX", $3); print}' test.txt

or

awk 'BEGIN{OFS=FS="\t"}{gsub(/^999$/, "XXX", $3); print}' OFS="\t" test.txt

See man awk