6/26/2023 0 Comments Keyboard key codesSince 2.6.9 there also is the boot option atkbd.softraw=0 that tells the 2.6 kernel to return the actual scan codes. So, if you want to know the scan codes sent by various keys it is better to boot a 2.4 kernel. ![]() Various transformations are involved, and there is no guarantee at all that the final result corresponds to what the keyboard hardware did send. Scan codes are first translated to key codes, and when scancodes are desired, the key codes are translated back. In 2.6 kernels raw mode, or scancode mode, is not very raw at all. The high order bits are: 0/1 for make/break, 1, 1. Key codes larger than 127 are returned as three bytes of which the low order 7 bits are: zero, bits 13-7, and bits 6-0 of the key code. In 2.6 kernels key codes lie in the range 1-255, instead of 1-127. This is the default, when no command line options are present. Showkey prints to the standard error output its version number, a compile option and a short usage message, then exits. When in `ascii' dump mode, showkey prints to the standard output the decimal, octal, and hexadecimal value(s) of the key pressed, according to he present keymap. Using showkey in this mode, you can find out what numbers to use in your personalized keymap files. Every key has always only one associated keycode number, whether the keyboard sends single or multiple scan codes when pressing it. Keycodes are numbers assigned by the kernel to each individual physical key. The kind of the event, press or release, is also reported. When in the default keycode dump mode, showkey prints to the standard output the keycode number or each key pressed or released. However, some modern keyboards have keys or buttons that produce scancodes to which the kernel does not associate a keycode, and, after finding out what these are, the user can assign keycodes with setkeycodes(8). As such it shouldn't be of much interest to the regular end-user. The scan code dumping mode is primarily intended for debugging the keyboard driver or other low level interfaces. This can be used to determine roughly, what byte sequences the keyboard sends at once on a given key press. A new line is printed when an interval of about 0.1 seconds occurs between the bytes received, or when the internal receive buffer fills up. When in scancode dump mode, showkey prints in hexadecimal format each byte received from the keyboard to the standard output. In `ascii' mode the program terminates when the user types ^D. In the first two modes the program runs until 10 seconds have elapsed since the last key press or release event, or until it receives a suitable signal, like SIGTERM, from another process. ![]() Showkey prints to standard output either the scan codes or the keycode or the `ascii' code of each key pressed. Examine the codes sent by the keyboard Synopsis
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