Batch script - run simulation

[Adila]

I'm editing the startxwin.bat which came with cygwin
What I'm trying to do is, to be able to run a ns simulation automatically when I open the batch file without having to type this command:

ns example.tcl

I'm not sure if I'm on the right track, I've been playing around with:

call %HOME%\example.tcl
REM %RUN% ns example.tcl
REM %ns %HOME%\example.tcl

but none of it do as I wanted :(

Is there anything specific that I should try using?

Thanks