Setting environment variables using system commands

Developer Resources > Environment Variables >

The variables set in the operating system take priority over any settings in the Maya.env file. However, when Maya verifies the environment settings, it may add default settings.

On Linux, you can use setenv to set environment variables. You can add commands to you .cshrc file to make sure the environment variables are always available.

setenv MAYA_SCRIPT_PATH /remote/scriptDisk/scriptFiles/

On the Maya command line, you can use the MEL command putenv to set environment variables.

putenv "MAYA_SCRIPT_PATH" "/remote/scriptDisk/scriptFiles/";

On Windows, right-click My Computer and choose Properties (or double-click System in the control panel), then click the Advanced tab, and click Environment Variables.
On Mac OS X, you can set environment variables in a shell as described above in the Linux section. However, those variables will only be available if you run Maya from the shell. If you run Maya from the Dock, it will not use any of the environment variables from your shell. Therefore, on Mac OS X, it is strongly suggested that you place your environment variable settings in a Maya.env file.