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.

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.

• Nazarov Denis
• Andrey Bychkov

• evtest
• evtest-debuginfo