post build conditions

Hi ive just started using build events so im not very good at it yet, ive managed to rename an assembly once compiled like this

rename $(TargetFileName) $(TargetName).customextention

which changes the extention from .exe/.dll to .customextention

however once compiled and renamed, when i compile my solution without making changes to that project i get an error saying it cant rename a file that isnt there. so my question is how do i do something like this which doesnt work

if Exists $(TargetFileName) rename $(TargetFileName) $(TargetName).customextention

My error is because $(TargetName).customext already exists so what i actualy need to do is

if exists $(TargetName).customext delete $(TargetName).customext

so to ammend my question how do i do that?

What about:

Code:

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move /y $(TargetFileName) $(TargetName).customextention

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