I need some help. I been doing system admin for the last several years and gotten very rusty on scripting. I need to write a script that will take a log entry and do math using two columns of data to create a new column. I am taking the column(#2) that contains the time and the column(#5) that contains transaction milliseconds and subracting that column for the time column to create a new column in the file. I am butting my head against my screen trying to remember who to do it. Here is an example of my log entry.

20070401 004639826 decode 10578 2770 2.77 00:46:37 29.728125 10.732
17509

So to make it easier to understand if I didn't above(up for about 20 hours working on a project so I might be a little fuzzy, LOL)
I want something that does this:
004639826 - 2770 = 004637056
And overwrites the 004637056 to column 8 to have the following output:
20070401 004639826 decode 10578 2770 2.77 004637056 29.728125 10.732
17509


I much appreciate any help that you can provide.


Thanks in Advance.

Scott