An .exe is NOT a batch so no need to "call" it, just execute it.
What you're trying to do only works with SVN builds, as far as I recall, and the format for the parameter is

1config -set "sdl sensitivity=900"

what's the problem with restarting dosbox?

@bloodbat
Thank you very much for your answer!
I've downloaded the EmuCR-Dosbox-r3829 binary, removed the "call" instruction and tried your command, but it still doesn't work, the sensitivity of the mouse remains unchanged in X-Wing.

The resulting batch is:

1config -set "sdl sensitivity=900"
2sensitivity>resultat.txt
3xwing.exe
4config -set "sdl sensitivity=100"
5sensitivity>>resultat.txt

And the text file "resultat.txt" gives these values, which confirms the sensitivity does change, however it has no effect in game:

1900
2100

Maybe I did not choose the correct SVN Build, do you have a piece of advice to pick the correct one ?
Thank you again for your help.

@robertmo
There is of course no matter at all with DosBox 0.74, I do not imply that it's not good or anything of this kind. I'm trying to change the mouse sensitivity value on the fly because I use to launch Norton Commander in the autoexec and it requires the default value of 100. This is a pure "quest for personnal comfort", a solution is not mandatory at all !
edit: once again I am sorry for my english !

If a config setting is changeable at runtime it's enough to type it as a command followed by a parameter. (e.g. "sensitivity 100" at the prompt)

Though you've already confirmed that DOSBox registers your change, so if the mouse is not affected in-game, it might be an issue with SDL...
It seems you're using Windows - try opening a command prompt window, then type "set SDL_VIDEODRIVER=WINDIB", and launch DOSBox from the command line. See if you notice any changes.

VileRancour wrote:

try opening a command prompt window, then type "set SDL_VIDEODRIVER=WINDIB", and launch DOSBox from the command line. See if you notice any changes.

Hi, thank you for your answer !
I just tried it and it is the same thing, the sensitivity is modified when I call its value or redirect it in a text file, but it has still no effect in game.
What is puzzling me is the fact that setting the 900 value in my dosbox.conf file does work (of course the cursor gets far too fast in Norton Commander or other games in the current DosBox session).
I'm quite ignorant of the inner mechanisms of DosBox and Windows, do you think using a GNU/Linux DosBox build might solve my problem ?

Funny...I just tried changing it on the fly and it didn't work for me either.
Perhaps, being an SDL property and all...it can't be changed on the fly?
The same thing will result if trying to change the output on the fly (no change).
With a decent .conf file or front-end, you'd be set...no need to launch Norton Commander, it creates an unnecesary problem with what seems like an impractical solution. Or you could learn the Norton Commander hotkeys 😜

Hmm. Yes, looking at the code, both "sensitivity" and "output" are changeable on the fly as far as DOSBox is concerned, but SDL probably knows nothing of that, so whatever value is set at launch will be used for the whole session.
The OS shouldn't matter... that was just a diagnostic step. As bloodbat says, I guess you'd be better off with a game-specific .conf file (or a frontend to manage that for you).

Understood. Thanks to both of you for your help and advice, I sure can live with game specific .conf files and restarts.
Regards,
mb