From QB64 Wiki
The SYSTEM statement immediately closes a program and in DOS and can avoid returning to the QBasic IDE.
- SYSTEM [return_code%]
- QB64 allows a code number to be used after SYSTEM to be read in another program module by the SHELL or _SHELLHIDE functions.
- This command should be used to close a program quickly instead of pausing with END or nothing at all.
- A code can be added after the statement to send a value to the SHELL (function) or _SHELLHIDE function in another module.
- If a program BAS module is run from the IDE, stopped by Ctrl-Break or an error occurs the QB program will exit to the IDE.
- In QB64 SYSTEM ends the program and closes the window immediately. The last screen image may not be displayed.
- Qbasic BAS files can be run like compiled programs without returning to the IDE when SYSTEM is used to end them!
- To run a QuickBasic program without the IDE use the following DOS command line: QB.EXE /L /RUN filename.BAS