Getevent

The getevent tool runs on the device and provides information about input devices and a live dump of kernel input events.

It is very useful tool for ensuring that device drivers are reporing the expected set of capabilities for each input device and are generating the desired stream of input events.

Usage

Showing Device Capabilities

It is often quite useful to see all of the keys and axes that a device reports. Use the -p option to do that.

Here is a list of all of the Linux key codes and other events that a particular keyboard says it supports.

$ adb shell su -- getevent -p

  name:     "Motorola Bluetooth Wireless Keyboard"
  events:
    KEY (0001): 0001  0002  0003  0004  0005  0006  0007  0008 
                0009  000a  000b  000c  000d  000e  000f  0010 
                0011  0012  0013  0014  0015  0016  0017  0018 
                0019  001a  001b  001c  001d  001e  001f  0020 
                0021  0022  0023  0024  0025  0026  0027  0028 
                0029  002a  002b  002c  002d  002e  002f  0030 
                0031  0032  0033  0034  0035  0036  0037  0038 
                0039  003a  003b  003c  003d  003e  003f  0040 
                0041  0042  0043  0044  0045  0046  0047  0048 
                0049  004a  004b  004c  004d  004e  004f  0050 
                0051  0052  0053  0055  0056  0057  0058  0059 
                005a  005b  005c  005d  005e  005f  0060  0061 
                0062  0063  0064  0066  0067  0068  0069  006a 
                006b  006c  006d  006e  006f  0071  0072  0073 
                0074  0075  0077  0079  007a  007b  007c  007d 
                007e  007f  0080  0081  0082  0083  0084  0085 
                0086  0087  0088  0089  008a  008c  008e  0090 
                0096  0098  009b  009c  009e  009f  00a1  00a3 
                00a4  00a5  00a6  00ab  00ac  00ad  00b0  00b1 
                00b2  00b3  00b4  00b7  00b8  00b9  00ba  00bb 
                00bc  00bd  00be  00bf  00c0  00c1  00c2  00d9 
                00f0  0110  0111  0112  01ba 
    REL (0002): 0000  0001  0008 
    ABS (0003): 0028  : value 223, min 0, max 255, fuzz 0, flat 0, resolution 0
                0029  : value 0, min 0, max 255, fuzz 0, flat 0, resolution 0
                002a  : value 0, min 0, max 255, fuzz 0, flat 0, resolution 0
                002b  : value 0, min 0, max 255, fuzz 0, flat 0, resolution 0
    MSC (0004): 0004 
    LED (0011): 0000  0001  0002  0003  0004 
  input props:
    <none>

The -i option shows even more information than -p, including HID mapping tables and debugging information.

The -l option uses textual labels for all event codes, which is handy.

$ adb shell su -- getevent -lp /dev/input/event1

  name:     "Melfas MMSxxx Touchscreen"
  events:
    ABS (0003): ABS_MT_SLOT           : value 0, min 0, max 9, fuzz 0, flat 0, resolution 0
                ABS_MT_TOUCH_MAJOR    : value 0, min 0, max 30, fuzz 0, flat 0, resolution 0
                ABS_MT_POSITION_X     : value 0, min 0, max 720, fuzz 0, flat 0, resolution 0
                ABS_MT_POSITION_Y     : value 0, min 0, max 1280, fuzz 0, flat 0, resolution 0
                ABS_MT_TRACKING_ID    : value 0, min 0, max 65535, fuzz 0, flat 0, resolution 0
                ABS_MT_PRESSURE       : value 0, min 0, max 255, fuzz 0, flat 0, resolution 0
  input props:
    INPUT_PROP_DIRECT

Showing Live Events

This is what a two finger multitouch gesture looks like for a touch screen that is using the Linux multitouch input protocol "B". We use the -l option to show textual labels and -t to show timestamps.

$ adb shell su -- getevent -lt /dev/input/event1

[   78826.389007] EV_ABS       ABS_MT_TRACKING_ID   0000001f
[   78826.389038] EV_ABS       ABS_MT_PRESSURE      000000ab
[   78826.389038] EV_ABS       ABS_MT_POSITION_X    000000ab
[   78826.389068] EV_ABS       ABS_MT_POSITION_Y    0000025b
[   78826.389068] EV_ABS       ABS_MT_SLOT          00000001
[   78826.389068] EV_ABS       ABS_MT_TRACKING_ID   00000020
[   78826.389068] EV_ABS       ABS_MT_PRESSURE      000000b9
[   78826.389099] EV_ABS       ABS_MT_POSITION_X    0000019e
[   78826.389099] EV_ABS       ABS_MT_POSITION_Y    00000361
[   78826.389099] EV_SYN       SYN_REPORT           00000000
[   78826.468688] EV_ABS       ABS_MT_SLOT          00000000
[   78826.468688] EV_ABS       ABS_MT_TRACKING_ID   ffffffff
[   78826.468719] EV_ABS       ABS_MT_SLOT          00000001
[   78826.468719] EV_ABS       ABS_MT_TRACKING_ID   ffffffff
[   78826.468719] EV_SYN       SYN_REPORT           00000000