UniPCemu supports various command-line parameters:

• nowpbios: An alternative to the normal BIOS write protect lifting.
• multiplayerjoysticks
  • Makes joysticks only connect to the instance when connected while UniPCemu has focus. They always keep responding when this parameter is given, even when the window doesn't have focus (focus is effectively ignored for the joystick).
• nosound
  • Disables sound output functionality
• rdp
  • Assumes RDP is active and mouse needs position patching.
• dumpbios
  • Dump the BIOS ROM to ROMDMP.<architecture>.BIN
• nosleep
  • Prevent Windows from going into sleep/hiberate while the app is running.
• fullscreenwindow
  • Make SDL2 stretch the window to become the entire desktop area when not in fullscreen mode.
• debuggerqemu
  • Enables limited logging on the Qemu debugger output port (port 402h).
• debuggerout
  • prints debugger.log output to stdout as well.
• debuggerin
  • reads debugger.log verification from stdin. If a mismatch occurs on a line, "<VERIFY:MISMATCH>" (without quotes) is logged on the line following it.
• --version (linux only)
  • Displays the commit version that was used when compiling the executable.

Linux-based builds besides Android also have an environment variable named UNIPCEMU that can override the default folder to run the application in (where all it's filed are located). This can be set as long as the path is longer than 1 character. A slash will be added to this if the final character in the path isn't already a trailing slash. By default (if unspecified or invalid), this is "~/UniPCemu", with the path specified by SDL 2.0 and up having priority over that home directory path. It can be set to the current working directory by specifying a simple dot (".") as the value of the environment variable. All other single-character paths are detected as invalid and will use the SDL2 method of retrieval with fallback to the home directory folder "UniPCemu".