Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
EVTEST(1)							     EVTEST(1)

NAME
       evtest -	Input device event monitor and query tool

SYNOPSIS
       evtest [--grab] /dev/input/eventX

       evtest --query /dev/input/eventX	<type> <value>

DESCRIPTION
       The first invocation type displayed above ("capture mode") causes
       evtest to display information about the specified input device,
       including all the events	supported by the device. It then monitors the
       device and displays all the events layer	events generated.

       If the --grab flag is given in capture mode, evtest keeps an EVIOCGRAB
       on the device. While this grab is active, other processes will not
       receive events from the kernel devices. The grab	is released again when
       evtest quits.

       In the second invocation	type ("query mode"), evtest performs a
       one-shot	query of the state of a	specific key value of an event type.

       type is one of: EV_KEY, EV_SW, EV_SND, EV_LED (or the numerical value)

       value can be either a decimal representation (e.g. 44), hex (e.g.
       0x2c), or the constant name (e.g. KEY_Z)	of the key/switch/sound/LED
       being queried.

       If the state bit	is set (key pressed, switch on,	...), evtest exits
       with code 10. If	the state bit is unset (key depressed, switch off,
       ...), evtest exits with code 0. No other	output is generated.

       evtest needs to be able to read from the	device;	in most	cases this
       means it	must be	run as root.

       evtest is commonly used to debug	issues with input devices in X.Org.
       The output of evtest shows the information presented by the kernel;
       based on	this information it can	be determined whether a	bug may	be a
       kernel or an X.Org issue.

DIAGNOSTICS
       If evtest does not show any events even though the device is being
       used, the device	may be grabbed by a process (EVIOCGRAB). This is
       usually the case	when debugging a synaptics device from within X. VT
       switching to a TTY or shutting down the X server	terminates this	grab
       and synaptics devices can be debugged.

       The following command shows the processes with an open file descriptor
       on the device:

	   fuser -v /dev/input/eventX

EXIT CODE
       evtest returns 1	on error.

       When used to query state, evtest	returns	0 if the state bit is unset
       and 10 if the state bit is set.

SEE ALSO
       inputattach(1)

AUTHOR
       evtest was written by Vojtech Pavlik <vojtech@suse.cz[1]>.

       This manual page	was written by Stephen Kitt <steve@sk2.org[2]>,	based
       on that present in the lineakd package, for the Debian GNU/Linux	system
       (but may	be used	by others).

NOTES
	1. vojtech@suse.cz
	   mailto:vojtech@suse.cz

	2. steve@sk2.org
	   mailto:steve@sk2.org

				  08/27/2021			     EVTEST(1)

NAME | SYNOPSIS | DESCRIPTION | DIAGNOSTICS | EXIT CODE | SEE ALSO | AUTHOR | NOTES

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=evtest&sektion=1&manpath=FreeBSD+13.0-RELEASE+and+Ports>

home | help