# 3 .
Don't know how Cygwin works.
If is like a normal Linux OS, you can have an infinite number
of executable ns in /usr/local/bin/ : ns ns-orig ns229 ns234 etc. etc.
I.e. the trick is to use different names for all your "ns executable".
(Or you can use './ns' instead of having ns in a particular PATH.)
Most simulations will work with any name for 'ns' :
$ ns229 example.tcl , $ ns234 example.tcl , etc.