Hi,
The contents of my file is below:

Name,Location,Degree,Gender,Awards
Robert,Philadelphia,Accounting,Male,5
Jane,Chicago,Business,Female,2
Allan,New York,Engineering,Male,6
Tom,Detroit,Computer Science,Male,10
Nancy,Milwaukee,Engineering,Female,4

I want to add a "ID" in the 1st line
and the default codes (001) in front of the 2nd to last line.
Also, to insert a Salary (which is default at 3000) after the Degree field.
Output should now look like below:

ID,Name,Location,Degree,Salary,Gender,Awards
001,Robert,Philadelphia,Accounting,3000,Male,5
001,Jane,Chicago,Business,3000,Female,2
001,Allan,New York,Engineering,3000,Male,6
001,Tom,Detroit,Computer Science,3000,Male,10
001,Nancy,Milwaukee,Engineering,3000,Female,4

Would anyone be able to suggest?
Thanks.

awk '{ if(FNR==1) 
             {print "ID,", $0;}
         else
             {print "001,", $0}
       }' inputfile > newfile

Try:

awk -F"," '{ OFS=",";  if (NR==1)
                { $3=$3",Salary,"; print "ID,"$0; }
                else
                        {$3=$3",3000,";$1="001,"$1; print $0; }
                        }'  < filename