README (1954B)
1 VHIDKB(1) User Commands VHIDKB(1) 2 3 NAME 4 vhidkb - virtual HID keyboard 5 6 SYNOPSIS 7 vhidkb [-h] [-d DEVICE] [-t DELAY] 8 9 DESCRIPTION 10 vhidkb creates a virtual 256-key HID keyboard with N-key rollover using 11 the Linux /dev/uhid interface. Each key starts in the released state, 12 and each byte received over stdin toggles the key of that number. Keys 13 are numbered in accordance with the HID usage page 0x07. vhidkb 14 destroys the virtual keyboard and exits after reaching EOF. 15 16 OPTIONS 17 -h Display a help message. 18 19 -d DEVICE 20 Use DEVICE as the /dev/uhid interface instead of "/dev/uhid". 21 22 -t DELAY 23 Wait DELAY milliseconds after the first process opens the HID 24 device before sending key events. If DELAY is negative, then key 25 events are sent even if no process has the HID device open. By 26 default, vhidkb acts as if "-t 100" is passed as an option. 27 28 NOTES 29 The -t option exists as a hack to solve timing issues where an X server 30 opens the HID device, closes it, and then opens it again, all within a 31 few tens of milliseconds. (Why does Xorg do this? I don't know.) With 32 0ms DELAY, the first opening causes vhidkb to start sending key events 33 (assuming some data is available on stdin), but these events will most 34 likely end up being discarded. 35 36 By default, accessing /dev/uhid requires root privilages. For easy and 37 secure use, the author recommends creating a "uhid" group for the 38 /dev/uhid device and the vhidkb executable, with the latter having its 39 set-group-ID bit set. Changing the group of /dev/uhid can be automated 40 in init scripts. 41 42 SEE ALSO 43 HID Usage Tables <https://usb.org/sites/default/files/hut1_3_0.pdf> 44 45 vhidkb 2022-08-29 VHIDKB(1)