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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | 2.6 KERNELS | SEE ALSO | COLOPHON |
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SHOWKEY(1) General Commands Manual SHOWKEY(1)
showkey - examine the codes sent by the keyboard
showkey [-h|--help] [-a|--ascii] [-s|--scancodes] [-k|--keycodes]
[-V|--version]
showkey prints to standard output either the scan codes or the
keycode or the `ascii' code of each key pressed. 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. In `ascii'
mode the program terminates when the user types ^D.
When in scancode dump mode, showkey prints in hexadecimal format
each byte received from the keyboard to the standard output. 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. This can be used to determine roughly, what byte
sequences the keyboard sends at once on a given key press. The
scan code dumping mode is primarily intended for debugging the
keyboard driver or other low level interfaces. As such it
shouldn't be of much interest to the regular end-user. 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).
When in the default keycode dump mode, showkey prints to the
standard output the keycode number or each key pressed or
released. The kind of the event, press or release, is also
reported. Keycodes are numbers assigned by the kernel to each
individual physical key. Every key has always only one associated
keycode number, whether the keyboard sends single or multiple
scan codes when pressing it. Using showkey in this mode, you can
find out what numbers to use in your personalized keymap files.
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.
-h --help
showkey prints to the standard error output its version
number, a compile option and a short usage message, then
exits.
-s --scancodes
Starts showkey in scan code dump mode.
-k --keycodes
Starts showkey in keycode dump mode. This is the default,
when no command line options are present.
-a --ascii
Starts showkey in `ascii' dump mode.
-V --version
showkey prints version number and exits.
In 2.6 kernels key codes lie in the range 1-255, instead of
1-127. 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. The high order bits are: 0/1 for make/break, 1, 1.
In 2.6 kernels raw mode, or scancode mode, is not very raw at
all. Scan codes are first translated to key codes, and when
scancodes are desired, the key codes are translated back. Various
transformations are involved, and there is no guarantee at all
that the final result corresponds to what the keyboard hardware
did send. So, if you want to know the scan codes sent by various
keys it is better to boot a 2.4 kernel. Since 2.6.9 there also is
the boot option atkbd.softraw=0 that tells the 2.6 kernel to
return the actual scan codes.
loadkeys(1), dumpkeys(1), keymaps(5), setkeycodes(8)
This page is part of the kbd (Linux keyboard tools) project.
Information about the project can be found at
⟨http://www.kbd-project.org/⟩. If you have a bug report for this
manual page, send it to [email protected]. This page was
obtained from the project's upstream Git repository
⟨https://github.com/legionus/kbd.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-05-20.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
kbd 1 Feb 1998 SHOWKEY(1)
Pages that refer to this page: loadkeys(1), keymaps(5), setkeycodes(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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