You can use the simulation run control (.simrc) file to customize simulations. This file lets you set your defaults for the simulation variables. It overrides the contents of the si.env file. Therefore, the .simrc file provides a mechanism to set the defaults at the user or flow level. This file is optional and is loaded if it exists.
If you want to use another file, instead of .simrc, to customize simulations for a specific flow, use the UNIX environment variable ossUserSimrc to set the path of that custom file. For example, the following command sets mysimrc as the custom file.
$ setenv ossUserSimrc mysimrc
The functionality provided by ossUserSimrc lets you customize the simulation environment to suit the specific requirements of different flows, without changing your .simrc file. If ossUserSimrc is not set, then the default CSF mechanism is used to load the simulation customization file.