Hi ilan,
Thanks for taking this up ... I have the first piece figured out ... I can generate a random number using a small perl script that I downloaded of the net ... but I have a problem with the second part ... I'll try to describe it better.

I have 50 million records with 2 columns. Both the columns are present in all the records.

Step1: Generate a random value (this is the part i figured out above)
Step2: Locate a random record among the 50 million
Step3: Replace the value in the second column with the value generated in step 1.
Step4: Go back to Step1, generate a new value, look for another random record, replace it with this value and so on for about a million times.

I want to be able to do this in place since everytime I replace a record using awk, it gives the whole 50 million inclusive of that change as the output and i have redirect the output to another file, rename it to the original and start over again for the next iteration.
What I need is a way to edit the file in place in a loop identifying random records and changing the second column a million times.


The high level requirement is:
Given a file of 50 million records, I have to generate a file that has 50 million records but has 1 million records whose second column varies from that of the first file. Maybe there is an easier way to do this ... But I am stumped right now ....


Thanks,
V