awk + add column without adding to header

Question

I am working on this awk tutorial here .

$ head file
Name,Number,Letter
Unix,10,A
Linux,30,B
Solaris,40,C
Fedora,20,D
Ubuntu,50,E

this command inserts a new column after the last column. But i do not want to add to the header, how do I do this? I will also, after this, want to add a header name after.

$ awk -F, '{$(NF+1)=++i;}1' OFS=, file
Name,Number,Letter,1
Unix,10,A ,2
Linux,30,B ,3
Solaris,40,C ,4
Fedora,20,D ,5
Ubuntu,50,E,6

Answer 1

You can skip the first line with:

awk -F, 'NR>1{$(NF+1)=++i;}1' OFS=, file

If there can be blanks in the file, then you can use regular expression to mask them out:

awk -F, '!/^$/ && NR>1{$(NF+1)=++i;}1' OFS=, file

To add a new header, you can do:

awk 'NR==1{$0=$0",New_header";} NR>1{$(NF+1)=++i;}1' OFS=, file

Like @jaypal said, it could be simply:

awk -F, 'NR==1{$0=$0",New_header";} NF && NR>1{$(NF+1)=++i;}1' OFS=, file

Answer 2

$ awk 'BEGIN{FS=OFS=","} {print $0, (NR>1?NR-1:"new header")}' file
Name,Number,Letter,new header
Unix,10,A,1
Linux,30,B,2
Solaris,40,C,3
Fedora,20,D,4
Ubuntu,50,E,5