Wolfram Research, Inc.
A.7.1 Command-Line Options and Environment Variables
Typical command-line options for Mathematica executables.
If the Mathematica front end is called with a notebook file as a command-line argument, then this notebook will be made the initial selected notebook. Otherwise, a new notebook will be created for this purpose.
Mathematica kernels and front ends can also take additional command-line options specific to particular window environments.
If no command-line options are explicitly given, Mathematica will read the values of operating system environment variables, and will use these values like command lines.