When you use GstarCAD, you’ll want to use it optimally right? You can see the command alias list and customize your own shortcuts by accessing edit aliases in ribbon> Manage tab> Customizes Settings panel> Edit Aliases. Or you can access it from menu> Tools> Customize>Edit Program Parameters (gcad.pgp)

As you can see, the list of all GstarCAD command aliases by default. So aliases for line is L. When I type L then [enter] will activate the line tool. Typing LA [enter] will open the layer manager. Etc. They are very useful shortcuts to work faster! You can edit the command aliases and change them to what you want. After you finish, save this file. You might need to restart your GstarCAD after doing your modification. Or you can run REINIT to reload your gcad.pgp.

Updates: 

There is another way to modify command aliases easily. You have to use express tool to do this. This tool name isCommand Alias Editor. You can access it from menu: Express>Tools>Command Alias Editor.