Category Archives: Ubuntu

Story of a bug in Ubuntu

I just came across this lovely writeup of a particularly annoying bug I helped squash in Ubuntu 12.04. The bug caused applications like evince and eog to load incredibly slowly, taking almost a full minute to open a PDF. It turned out to have a relatively banal cause — an initialization procedure didn’t immediately signal its failure and instead the library would wait a full 5 seconds for the initialization to finish before giving up.

Thanks for the writeup, Emanuele Rocca. I think this shows the power of open source software. An obscure bug affecting only a handful of people can still get fixed, even without much help from the original developers.

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Changing screen resolution in RealVNC

These days I do most of my work in a RealVNC session on a remote Ubuntu workstation. This provides me with a consistent environment, regardless of whether I’m at work, a coffee shop, or at home. One major annoyance with the default configuration is that the screen resolution cannot be changed after the virtual desktop is started.

The key to getting around this problem is to provide RealVNC with a complete list of screen resolutions you would like to have available when starting RealVNC. For example, my .vnc/config file contains

# Additional Resolutions
-randr 800x600,1024x768,1280x800,1280x960,1280x1024,1344x756,1680x1050,1920x1080,1920x1200,3360x1050,1024x700,1200x740,1600x1000,3200x1000,1680x1020,768x1024

After restarting RealVNC, you can easily change the screen resolution using the xrandr command. You can list screen resolutions by running xrandr:

$ xrandr
 SZ:    Pixels          Physical       Refresh
 0    800 x 600    ( 203mm x 152mm )   0
 1   1024 x 768    ( 260mm x 195mm )   0
 2   1280 x 800    ( 325mm x 203mm )   0
 3   1280 x 960    ( 325mm x 244mm )   0
 4   1280 x 1024   ( 325mm x 260mm )   0
 5   1344 x 756    ( 341mm x 192mm )   0
 6   1680 x 1050   ( 427mm x 267mm )   0
*7   1920 x 1080   ( 488mm x 274mm )  *0
 8   1920 x 1200   ( 488mm x 305mm )   0
 9   3360 x 1050   ( 853mm x 267mm )   0
 10  1024 x 700    ( 260mm x 178mm )   0
 11  1200 x 740    ( 305mm x 188mm )   0
 12  1600 x 1000   ( 406mm x 254mm )   0
 13  3200 x 1000   ( 813mm x 254mm )   0
 14  1680 x 1020   ( 427mm x 259mm )   0
 15   768 x 1024   ( 195mm x 260mm )   0
Current rotation - normal
Current reflection - none
Rotations possible - normal
Reflections possible - none

To switch to a different resolution just run xrandr -s <resolution>, where the resolution is either the item number, like 12, or resolution, like 1600x1000.

Afterwards, especially in recent versions of Ubuntu (12.04 and later), you may find that the background Nautilus desktop didn’t get the memo that the screen resolution was changed. To work around this, it’s often easiest to quit and restart Nautilus:

$ nautilus -q; sleep 1; nautilus -n > /dev/null 2>&1 & disown %

If you find yourself doing this a lot, as I did, you may want to consider writing a little script to automate the task. I named my script xres and have posted the source as a gist.