Capturing output from stderr

[Doru-Catalin Togea]

Hi!

On solaris, I call a program from python with

 	os.system("some command > outputFile.txt" )

This redirects the output of "some command"'s stdout to "outputFile.txt". 
However I need to redirect or somehow capture the output from "some 
command"'s stderr to this file too. How can I do that?

Thanks,
Catalin