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On Arch Linux running GNOME, if I press Shift+3, it locks X (nothing but the mouse cursor works).  All window updates are suspended.  The only option is to zap it with Ctrl+Alt+Backspace.

I've looked in logs, nothing. I've searched the web, nothing. I've tried every possible keypress, nothing.

Shift+2 works just fine, as does Shift+4.

I'm on a Mac Pro, with a UK Apple keyboard. I don't think this should matter, but it is the £ (pound) symbol that comes out on the console before I run startx. In X, I can use Alt+Shift+3 and get a pound without any problems. Alt+3 gives me # as expected.

Any ideas where to start with this? Is there extra logging I can somehow enable?


xmodmap -pke gives:

keycode 12 = 3 sterling 3 sterling numbersign sterling threesuperior sterling 3 sterling threesuperior sterling


xev output. I pushed x then Shift+3, then 1. Interestingly, it continued writing to the output after the DM froze.

KeyPress event, serial 36, synthetic NO, window 0xa00001,
root 0x4a3, subw 0x0, time 338011, (655,-7), root:(840,525),
state 0x10, keycode 53 (keysym 0x78, x), same_screen YES,
XLookupString gives 1 bytes: (78) "x"
XmbLookupString gives 1 bytes: (78) "x"
XFilterEvent returns: False

KeyRelease event, serial 36, synthetic NO, window 0xa00001,
root 0x4a3, subw 0x0, time 338091, (655,-7), root:(840,525),
state 0x10, keycode 53 (keysym 0x78, x), same_screen YES,
XLookupString gives 1 bytes: (78) "x"
XFilterEvent returns: False

KeyPress event, serial 36, synthetic NO, window 0xa00001,
root 0x4a3, subw 0x0, time 339867, (655,-7), root:(840,525),
state 0x10, keycode 62 (keysym 0xffe2, Shift_R), same_screen YES,
XLookupString gives 0 bytes: 
XmbLookupString gives 0 bytes: 
XFilterEvent returns: False

KeyPress event, serial 36, synthetic NO, window 0xa00001,
root 0x4a3, subw 0x0, time 340219, (655,-7), root:(840,525),
state 0x11, keycode 12 (keysym 0xa3, sterling), same_screen YES,
XLookupString gives 2 bytes: (c2 a3) "£"
XmbLookupString gives 2 bytes: (c2 a3) "£"
XFilterEvent returns: False

KeyRelease event, serial 36, synthetic NO, window 0xa00001,
root 0x4a3, subw 0x0, time 340299, (655,-7), root:(840,525),
state 0x11, keycode 12 (keysym 0xa3, sterling), same_screen YES,
XLookupString gives 2 bytes: (c2 a3) "£"
XFilterEvent returns: False

KeyRelease event, serial 36, synthetic NO, window 0xa00001,
root 0x4a3, subw 0x0, time 340411, (655,-7), root:(840,525),
state 0x11, keycode 62 (keysym 0xffe2, Shift_R), same_screen YES,
XLookupString gives 0 bytes: 
XFilterEvent returns: False

KeyPress event, serial 36, synthetic NO, window 0xa00001,
root 0x4a3, subw 0x0, time 349763, (655,-7), root:(840,525),
state 0x10, keycode 10 (keysym 0x31, 1), same_screen YES,
XLookupString gives 1 bytes: (31) "1"
XmbLookupString gives 1 bytes: (31) "1"
XFilterEvent returns: False

KeyRelease event, serial 36, synthetic NO, window 0xa00001,
root 0x4a3, subw 0x0, time 349835, (655,-7), root:(840,525),
state 0x10, keycode 10 (keysym 0x31, 1), same_screen YES,
XLookupString gives 1 bytes: (31) "1"
XFilterEvent returns: False
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  • 1
    Interesting. Does the system lock up hard, or you can e.g. still ssh into it from another computer and kill the X server, or X applications? Can you catch the shift-3 event with xev, or does it freeze before you see the result? Anything unusual on the '3' key (keycode 12, if the Mac keyboard is similar to PC keyboard) if you do xmodmap -pke?
    – dirkt
    Jan 31, 2017 at 13:08
  • it's a soft lock - ctrl-alt-backspace quits X, and the mouse still works, but the clock freezes along with all other window updates. I presume SSH still works. I'll try xev and xmodmap - thanks!
    – antonyh
    Jan 31, 2017 at 13:34
  • I just tried starting gdm first, and it works without issue. The thing is I use the console a lot, I go into X about 40% of the time.
    – antonyh
    Jan 31, 2017 at 13:58
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    So it's only an issue of you use startx directly, not with gdm? What window manager is run with startx? The sterling symbol is different than other keys in that it consists of two UTF-8 bytes, are any applications (including the window manager) running that could possibly choke on that? Can you try to ssh in after a freeze, and start killing X applications until you narrow it down to possible culprits? What happens you try to replace the sterling symbol with something else using xmodmap (see manpage how to do that)?
    – dirkt
    Jan 31, 2017 at 15:21
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    Do you have this problem with any other key, in particular ¬? Do you have this problem if you change to another keyboard layout (e.g. try a French keyboard layout and press Shift + the key that is ] in a UK/US layout to insert £)? Jan 31, 2017 at 23:07

2 Answers 2

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Removing dbus-launch --exit-with-session from .xinitrc appears to resolve this, for reasons unknown.

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very interesting.. I am running today - 5 years after orig post - in a very similar pattern.

I am running Manjaro (based on Arch Linux) since several months now and had rolling updates applied as they came in. Since a few days (weeks ?) i had irregular hangs on X11 as described above. For me this appears under the following conditions:

  • .xinitrc calls the "get_session" to get the dbus-launched
  • i enter the key with the German letter 'ß' w/o modifer-keys like Shift. (e.g. typing '?' which is on the same key, it is not freezing)

Things I have tried to narrow down:

  • new user (with no configs) - no influence
  • using icewm instead of plasma - no influence
  • commenting out the dbus-launching - fixes the problem
  • changing keymap to US - no influence

As this was working fluently a few weeks ago, i assume some software broke?any idea where to look at?

@antonyh Did you ever find out the reason?

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  • Sadly no, I never figured this one out.
    – antonyh
    Dec 9, 2022 at 8:59

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