How do i execute system commands in google app engine?

I am trying to execute simple system command via my servlet on google app engine. I'm not trying anything dangerous, just looking for simple stuff grep, sed, wget, find, etc.

Using java's Runtime class i keep getting access denied exceptions.

Do i have to get permission from google of some kind or ar开发者_JAVA技巧e shell commands banned period?

Fairly sure you can't do this.

An App Engine application cannot:

* make other kinds of system calls.