6

I need some clarification:

When I start xev in a terminal, and use Super, I get the following output. What is the meaning of this?

KeymapNotify event, serial 36, synthetic NO, window 0x0,
    keys:  2   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   
           0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   

FocusIn event, serial 36, synthetic NO, window 0x2000001,
    mode NotifyUngrab, detail NotifyNonlinear

KeymapNotify event, serial 36, synthetic NO, window 0x0,
    keys:  93  0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   
           0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0 
2
  • I'm wondering this as well: this probably explains it but it's extremely long
    – kos
    Sep 12 '15 at 16:39
  • Just for clarification, isn't the code you've shown only a small part of the output?
    – DK Bose
    Feb 17 '16 at 12:37
2

So after researching online for some time, here's my understanding of the output's meaning:

Take a look at the KeyPress and KeyRelease events from a letter key, like m.

KeyRelease event, serial 28, synthetic NO, window 0x6e00001,
    root 0x2c9, subw 0x0, time 17599679, (-746,426), root:(337,478),
    state 0x10, keycode 58 (keysym 0x6d, m), same_screen YES,
    XLookupString gives 1 bytes: (6d) "m"
    XFilterEvent returns: False

It has the keycode and reports the window id where the key has been pressed.

Function keys, like Fn+F6, which actually is the brightness decrease key, output no such information. They report 0x0 id for the window and no keykode. Thus, it means these keys cannot be reassigned and are controlled by software , like the X server or console; they are dependent on the environment in which they run. Which also somewhat explains why the Super key may or may not work within a particular desktop environment - it's up to the developers to include functionality of that key into their desktop environment.

MappingNotify event, serial 28, synthetic NO, window 0x0,
    request MappingKeyboard, first_keycode 8, count 248

KeymapNotify event, serial 29, synthetic NO, window 0x0,
    keys:  1   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   
           0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0  
3
  • So how does the two-row matrix of integers relate? what do its numbers mean?
    – matanster
    Jun 14 '20 at 7:19
  • @matanster Honestly , I don't know off the top of my head, because with any type of learning, it takes research, and right now I am in the middle of putting out a fire so to speak related to personal computing security, so admittedly I cannot answer this right now. Let's come back to this maybe in 30-60 days, depending on the urgency of the situation. Thank you for the comment ! I appreciate attention to my posts Jun 14 '20 at 9:22
  • I believe that matrix is the state of various toggle keys and such, sorry for bothering you with it after so long!
    – matanster
    Jun 14 '20 at 9:29

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