Electronic – STM32 – How to run the USB DFU In application programming, in Linux command line

There should be no real interaction between GDB or OpenOCD and the virtual serial port of an STM32 Discovery or Nucleo board, however the modemmanager package installed by default in Ubuntu and derived distributions will substantially delay availability of the CDC/ACM device after each reset, which typically includes not just connections but some programming operations (at least those using the mass storage emulation).

Things will work much better with modemmanger uninstalled. Please don't argue about this until you have actually tried removing it - the issue is behind the scenes, a delay in the operating system making the port available to user programs. It makes the difference between the boards being essentially useless, and working fairly well (a udev rule or driver blacklist to ignore the marginally broken mass storage emulation is a good idea, too)

You will however still probably need to establish appropriate serial line settings, with something like stty if not an actual terminal program - without that (and possibly even afterwards) you can't just go using something like cat that is ignorant of serial port details to interact with the port (though often if you do have a terminal program running, you can use echo or cat and a shell redirect alongside to write specific lines to it)

Does STM32 bootloader contains USB DFU?

Depends on the specific part. Refer to the part datasheet, or see AN2606 for a comprehensive overview.

For STM32F2 parts, it depends on the revision of the part. New parts (revisions X and Y) support USB DFU, but some older parts (revision B) do not.