Need help on run OS command

Dear Experts,

I am working on one requirement where i need to add .pgp extension to my source file name.

like this below example,

my source file :sf_out_123.txt

desired filename:sf_out_123.txt.pgp

my scenario is File(NFS)- SFTP(pass trhru) no ESR involved.

I have gone through this below blog

http://wiki.sdn.sap.com/wiki/pages/viewpage.action?pageId=272171407

we can acheive this using run OS command.

we are using windows server 2008. 

please provide me the suggestions to achieve my requirement.at sender comm channel(run OS command before processing)  end.

1) do we need any additional configuartion required to run OS command?(adding environment varibales, path .....etc)

2) what will be the sytnax to rename the file.

Thanks & Regards,

Pavan