15 GB free disk space in the cloud RecentChanges 2014-07-24 XML TXT

Latest weblog entries

2014-07-11 Xauthority doesn't exist

If you're connecting via SSH from OS X to Linux, you might get the following error:

  /opt/X11/bin/xauth:  file /Users/yourusername/.Xauthority does not exist

You can fix this by installing (or just running) XQuartz, available here.

2014-07-10 Unattended upgrades

I'm not normally prone to linking to stuff, but this is just too good:

Explains how you can get your Debian Wheezy box to automatically update. While this is bad practice for some situations like fragile production boxes, there's plenty of spaces where automatic updates work great: single-purpose machines like your (secondary) DNS, lonely virtual private servers with your home page, etc.

2014-05-16 VNC on Debian Wheezy

I recently discovered that VNC on Debian Wheezy is a bit of a mess.

VNC can be used in two modes: to mirror the actively running instance of X (i.e. the display on :0), or to have X running headless, in any resolution ("geometry") you want, on :1, :2, etc.

The version that comes with Wheezy by default, is an old version of TightVNC server. It doesn't support the alpha channel, so modern desktops like KDE 4 will look pretty bad.

Development has stopped on TightVNC, and continues in the TigerVNC project. There are packages available here, but these are pretty old now: version 1.1, while development has passed 1.3.

In and of itself that wouldn't be a problem, except the 1.1 version has a horrible bug where moving a window to the left will result in display artifacts.

You may also have found TurboVNC. Development seems to move slower but they do provide Debian packages. Unfortunately, even for the latest version it seems it suffers from the same bug.

There's a couple of options:

  • Build TightVNC yourself from the source files in the TigerVNC SourceForge downloads section. I tried this, and it's pretty daunting. I gave up after an hour of futzing.
  • Get the generic, statically linked binaries from the TigerVNC SourceForge downloads section, and then just unpack these in your filesystem root. This dumps some binaries here and there, and your sysadmin (or you yourself) will definitely consider this abuse of the sudo command.
  • Use the old TightVNC 1.1 version, which is nicely packaged, and live with the obvious bugs. Note that the above mentioned bug doesn't seem to manifest itself when exporting the currently running display on :0. On our in-house built software however, there's another issue where portions of the screen sometimes don't refresh.

I'm currently looking at other solutions such as X2Go, which seems to provide decent packages.

2014-05-07 Debian Wheezy interface without an IP address

Today, I needed to configure a machine so it brought up its ethernet interfaces without an IP address.

This is useful if you use such an interface with plain ethernet packets. For example, network sniffing or bridging stuff, but also when you communicate with custom electronics that speak plain ethernet.

To configure Debian Wheezy to bring up these interfaces without assigning an IP address, add the following stanza to /etc/network/interfaces:

 auto eth1
 iface eth1 inet static

You might also want to remove any IPv6 addresses from these interfaces. Stack Overflow told me to add the following line for each interface to /etc/network/interfaces:

 net.ipv6.conf.<interface>.disable_ipv6 = 1

2014-04-16 Python vi keybindings on OS X

If you're used to vi keybindings, and you use Python interactively, you're going to do a lot of cursing on OS X. This is because the readline library (responsible for keybindings and history) is GPL licensed and thus not distributed by Apple.

Here's a quick fix.

Add a file called .editrc with the following content:

 bind -v

Add a file called .pythonrc with the following lines:

 import rlcompleter
 import readline

Add a line to your .bashrc which makes Python run .pythonrc when it starts interactively:

 export PYTHONSTARTUP="$HOME/.pythonrc"

Start python from the commandline and voilĂ , enjoy history and vi keybindings and all that good stuff. Tested on 10.9.2 (Mountain Lion).


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