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Top Forums Programming Read 1 of 2 keyboards connected Post 302980896 by bakunin on Sunday 4th of September 2016 05:22:42 PM
Old 09-04-2016
Quote:
Originally Posted by SerKan
2 usb keyboards connected to a normal x86
One keyboard working as usual in xorg, but I need that the other one doesn't send anything to xorg but instead I want to process its keystrokes with some kind of background process.
First a bit of theory: you communicate with a UNIX system by using a "tty": a "terminal" consisting of a keyboard and a screen, usually connected via a serial line.

If you connect to a UNIX system over a network you use a so-called "terminal emulator program" (many times "xterm", but that is not the only one) to emulate such a terminal and its serial connection is emulated via the network connection.

There is a special form of a tty, which is called console. This is not connected via the standard serial line but directly attached to the computer. Perhaps the local screen attached to your VGA-card and the (first) keyboard form this console.

Now, after that much theory, to your specific question: this might work, but not necessarily with a USB-attached keyboard and definitely not with a background process. Background processes are part of a process hierarchy, headed by some foreground process: this is usually the shell from which you initiated the background process, typically by issuing the command:

Code:
$ /path/to/command -someoptions &

Since the shell you typed that in was already connected to some tty (the one which keyboard you used to type it, probably the console) the background process inherited this connection. You can cut it off from this (by using the nohup command) but per default itis attached to the one you used to call it. Furthermore, a single USB-attached keyboard is not a terminal.

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
 

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UKBD(4) 						   BSD Kernel Interfaces Manual 						   UKBD(4)

NAME
ukbd -- USB keyboard driver SYNOPSIS
To compile this driver into the kernel, place the following line in your kernel configuration file: device ukbd Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5): ukbd_load="YES" DESCRIPTION
The ukbd driver provides support for keyboards that attach to the USB port. usb(4) and one of uhci(4) or ohci(4) must be configured in the kernel as well. CONFIGURATION
By default, the keyboard subsystem does not create the appropriate devices yet. Make sure you reconfigure your kernel with the following option in the kernel config file: options KBD_INSTALL_CDEV If both an AT keyboard USB keyboards are used at the same time, the AT keyboard will appear as kbd0 in /dev. The USB keyboards will be kbd1, kbd2, etc. You can see some information about the keyboard with the following command: kbdcontrol -i < /dev/kbd1 or load a keymap with kbdcontrol -l keymaps/pt.iso < /dev/kbd1 See kbdcontrol(1) for more possible options. You can swap console keyboards by using the command kbdcontrol -k /dev/kbd1 From this point on, the first USB keyboard will be the keyboard to be used by the console. If you want to use a USB keyboard as your default and not use an AT keyboard at all, you will have to remove the device atkbd line from the kernel configuration file. Because of the device initialization order, the USB keyboard will be detected after the console driver initial- izes itself and you have to explicitly tell the console driver to use the existence of the USB keyboard. This can be done in one of the fol- lowing two ways. Run the following command as a part of system initialization: kbdcontrol -k /dev/kbd0 < /dev/ttyv0 > /dev/null (Note that as the USB keyboard is the only keyboard, it is accessed as /dev/kbd0) or otherwise tell the console driver to periodically look for a keyboard by setting a flag in the kernel configuration file: device sc0 at isa? flags 0x100 With the above flag, the console driver will try to detect any keyboard in the system if it did not detect one while it was initialized at boot time. DRIVER CONFIGURATION
options KBD_INSTALL_CDEV Make the keyboards available through a character device in /dev. options UKBD_DFLT_KEYMAP makeoptions UKBD_DFLT_KEYMAP=fr.iso The above lines will put the French ISO keymap in the ukbd driver. You can specify any keymap in /usr/share/syscons/keymaps with this option. options KBD_DISABLE_KEYMAP_LOADING Do not allow the user to change the keymap. Note that these options also affect the AT keyboard driver, atkbd(4). FILES
/dev/kbd* blocking device nodes EXAMPLES
device ukbd Add the ukbd driver to the kernel. SEE ALSO
kbdcontrol(1), ohci(4), syscons(4), uhci(4), usb(4), config(8) AUTHORS
The ukbd driver was written by Lennart Augustsson <augustss@cs.chalmers.se> for NetBSD and was substantially rewritten for FreeBSD by Kazutaka YOKOTA <yokota@zodiac.mech.utsunomiya-u.ac.jp>. This manual page was written by Nick Hibma <n_hibma@FreeBSD.org> with a large amount of input from Kazutaka YOKOTA <yokota@zodiac.mech.utsunomiya-u.ac.jp>. BSD
November 22, 2006 BSD
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