Make sure your script is readable by root only. And be root of course. Then only someone with root access to your machine can get at it. And if that happens, you have other problems.

If you can't be root, make it readable by you only. This doesn't exclude root from reading. If you don't trust root, you have a problem.

Any other approach that does not involve you typing in the actual password when the program needs running, will be rather easy to circumvent in my opinion. But of course I'm always open to other monks' opinions about this.

Liz