Tanguy Ortolo

Allowing computer suspend

Major desktop environments such as Xfce or KDE have a built-in computer suspend feature, but when you use a lighter alternative, things are a bit more complicated, because basically: only root can suspend the computer. Possible solutions include:

• using sudo to allow members of a given group to run a suspend command, e.g. pm-suspend as root;
• using a D-Bus UPower thingy, which communicates with a running daemon upowerd:

  $ dbus-send --system --print-reply \
              --dest='org.freedesktop.UPower' \
              /org/freedesktop/UPower org.freedesktop.UPower.Suspend
          

With recent updates of the related Debian packages — no idea of which one exactly — the latter solution may not work any more, in which case it will only return the following error:

Error org.freedesktop.UPower.GeneralError: not authorized

It appears that this error is linked to ConsoleKit, a part of all this modern *Kit gizmo pile. If you are in this case, try prefixing your session launcher with the undocumented dark magic call ck-launch-session. For instance, this is what I have in my .xsession to launch my window manager i3:

exec ck-launch-session i3

Note: I do not know what ck-launch-session does exactly, why it is needed, and I do not want to know. To me, all that WhatsitKit pile is just some opaque, under-documented — as in: no man page — crap, that no one but their author really understand, designed to solve theoretical problems no one really cares about — like: how to allow locally connected users to use the sound card while forbidding it to remote users — while creating new issues such as this one. This stuff is too complex and under-documented for me to dive into it, so if it does not work out of the box, it is just some crap that gets in my way to using my computer as I wish.

Disabling a monitor

In some configurations, you have two monitors and want to disable one. For instance, in addition to my LCD monitor, I have a projector which I only use for movies. According to xorg.conf's man page, it can be disabled this way:

Section "Device"
    Identifier  "Internal graphic card"
    Option      "Monitor-DVI"   "LCD Monitor"
    Option      "Monitor-VGA"   "Projector"
EndSection

Section "Monitor"
    Identifier  "LCD Monitor"
EndSection

Section "Monitor"
    Identifier  "Projector"
    Option      "Enable"    "false"
EndSection

Except that does not work, because contrary to what the man page says the real option to use is not Enable but Disable! So here is the correct configuration to disable that monitor at start-up:

Section "Device"
    Identifier  "Internal graphic card"
    Option      "Monitor-DVI"   "LCD Monitor"
    Option      "Monitor-VGA"   "Projector"
EndSection

Section "Monitor"
    Identifier  "LCD Monitor"
EndSection

Section "Monitor"
    Identifier  "Projector"
    Option      "Disable"   "true"
EndSection

Note: yes, I will send a bug report with a patch against xorg.conf's man page.

I just received an USB headset from Plantronics. Since it has a keypad on it, with buttons to mute the microphone and to adjust the volume, it appears as both a sound card and a keyboard. Problem: that keyboard sends a mouse ButtonPress 1 (yes, a mouse button event, do not ask me how that is materially and logically possible) when the microphone is muted, and only sends the corresponding ButtonRelease 1 when it is unmuted. As a result, the pointer behaves as if the mouse button was pressed continuously, rendering the desktop quite unusable.

Read more Using a Plantronics USB headset under X.Org/Linux

I have just bought a gamepad, the Saitek V.3 Cyborg Rumble Pad (also marketed as PS2700), mainly to play at SuperTuxKart under Debian GNU/Linux.

It works perfectly, except for one minor feature, and it can be used for playing and as an X11 input device.

Read more Using a gamepad under GNU/Linux