xsession-errors

Ever since I upgraded my notebook with a SSD, I was looking for a way to minimise or avoid unnecessary write accesses. The tools of choice (on Linux at least) are iostat for a rough summary and pidstat for the details. With the help of those two one can easily figure out which processes are responsible for write accesses.

Once a writing process is identified, lsof can tell you which files are actually written. Depending on what you want to achieve, you can then continue to relocate that file to a different disk (e.g. if you have two disks and want one of them to sleep most of the time) or to memory (using tmpfs). The latter obviously means that the written data will be lost at the next reboot, but sometimes this is perfectly fine e.g. for the files inside /tmp. Therefore, it is generally a good idea to move that directory into volatile memory following the instructions on the openSUSE Wiki.

All good and well if you actually manage to relocate or move a file. Often file locations are a matter of configuration and otherwise you can help yourself with dynamic links. But there was one very special file on my openSUSE 11.4 installation that withstood all my assaults for quiet some time. I’m speaking of a beast called .xsession-errors residing in your $HOME directory. Created by KDM, one would expect to be able to configure the location of that file. Indeed, there is a configuration option called ClientLogFile specifically for that purpose. Unfortunately this is only the first and easier of two necessary steps:

  1. As root open your /usr/share/kde4/config/kdm/kdmrc, go to a section labelled [X-:0-Core] (there may be multiple of those, but don’t worry and just pick the last one) and add the following line:
    ClientLogFile=../../tmp/xsession-errors-%u

    This will move the file into the /tmp directory. Mind the path relative to $HOME.

  2. Now the hidden piece: again as root open your /etc/X11/xdm/Xsession and make the following changes (I deliberately use the patch syntax here i.e. remove lines with a minus sign and add those with a plus sign):
    --- Xsession.old        2011-05-01 19:46:40.000000000 +0200
    +++ Xsession    2011-05-02 22:18:39.000000000 +0200
    @@ -123,8 +123,8 @@
         # GDM seems to handle this its self
         test -z "$GDMSESSION" || break
    
    -    # Once if KDM does handle this its self
    -    #test -z "$KDMSESSION" || break
    +    # KDM handles this itself
    +    test -z "$KDE_SESSION_VERSION" || break
    
         # Avoid bad symbolic links
         case "$errfile" in

Done; logout, restart KDM, re-login and check if the xsession-errors* exists at the new location. If so, remove your old one and cheer to a long living SSD. Only, of course, if the new location is not on your SSD, but e.g. in memory. It doesn’t hurt to re-check with pidstat.

Enabling the suspend hotkey in KDE4

There are several reports of problems with the suspend hotkey on KDE4 [1] [2]. And there is even a bug report on that issue. Naturally, I wouldn’t write about this if I hadn’t experienced the same problem myself. I solved it by slightly modifiying the approach described at Linux Basement, avoiding the need to create a dedicated shell script somewhere.

This might not have been possible in KDE 4.2 (I haven’t verified), but it is in KDE SC 4.4. The Input Actions dialog (under System Settings) allows for the configuration of DBus calls from hotkeys. This was configured fast and works painless. I have exported the hotkey group and pasted the content below. To use it, save this as PowerManagement.khotkeys and import it in the Input Actions dialog.

[Data]
DataCount=1

[Data_1]
Comment=Power management mappings of XF86 events
DataCount=1
Enabled=true
Name=Power Management
SystemGroup=0
Type=ACTION_DATA_GROUP

[Data_1Conditions]
Comment=
ConditionsCount=0

[Data_1_1]
Comment=Enables suspend hotkey
Enabled=true
Name=Suspend
Type=SIMPLE_ACTION_DATA

[Data_1_1Actions]
ActionsCount=1

[Data_1_1Actions0]
Arguments=
Call=org.freedesktop.PowerManagement.Suspend
RemoteApp=org.freedesktop.PowerManagement
RemoteObj=/org/freedesktop/PowerManagement
Type=DBUS

[Data_1_1Conditions]
Comment=
ConditionsCount=0

[Data_1_1Triggers]
Comment=Simple_action
TriggersCount=1

[Data_1_1Triggers0]
Key=Sleep
Type=SHORTCUT
Uuid={c1706a53-bde8-4364-b0af-71e9c1be6b3f}

[Main]
AllowMerge=true
ImportId=Power Management
Version=2