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Full Discussion: Read 1 of 2 keyboards connected
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:
SerKan
 

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LEARN ABOUT OSF1

scc

scc(7)							 Miscellaneous Information Manual						    scc(7)

NAME

       scc - Serial keyboard/mouse/communications interface

SYNOPSIS

       controller   scc0   at tc0   slot 3   vector sccintr

DESCRIPTION

       Two  base  board  Zilog scc dual UARTS provide DEC 3000 series personal systems with keyboard, mouse, and serial communications interfaces.
       The serial communications interfaces can operate at baud rates from B50 to B57600 (see tty(7)).

       The driver for the scc interface supports hardware flow control using the Request to Send (RTS) and Clear  to  Send  (CTS)  signals.   When
       hardware  flow  control is enabled, the flow of input data is controlled by the RTS signal and the flow of output data is controlled by the
       CTS signal.  If the CTS signal is off, the driver will suspend output to that line until the CTS lead is reasserted.  Likewise, the  driver
       will  turn off the RTS lead to tell the device connected to the line to stop sending data as a result of congestion on the host side.  When
       the condition clears, the driver will turn on the RTS lead to tell the device to resume sending data.

       In alternate console configurations (that is, no graphics head), communications port 2 (/dev/tty01) becomes the system console. The  serial
       system console port always operates at 9600 BPS, 8-bits, no parity.  No modem or hardware flow control is supported.

RESTRICTIONS

       Data  communications  equipment attached to the console serial port in alternate console configurations must be set to 9600 BPS, 8-bits, no
       parity. The scc driver enforces this restriction.

       Only communications port 1 (/dev/tty00) includes full modem control.

FILES

       console terminal local terminal local terminal

RELATED INFORMATION

       console(7), devio(7), modem(7), tty(7), MAKEDEV(8) delim off

																	    scc(7)
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