Maybe old vray.exe has -cmdmode=2 option as in V-Ray Standalone
But when i try cmdmode with vray 3.4 and vray next, error occurs:
[2019/May/16|09:59:56] [24 MB] warning: The parameter ‘cmdMode’ has been removed and so it has been ignored!
Because vray.exe taske about 5- 10 seconds to load plugins, I want use cmdmode to reduce the loading plugin time. For example, i can have serveral vray.exe -cmdmode=2 running with all plugins loading first, and use some scripts to let each vray.exe to render immediately.