Another exciting event has just been announced for Dublin next year with an Open Source Software Barcamp planned for Dublin March 28th next year. And you could be one of the speakers! The idea behind a barcamp is to have a casual relaxed atmosphere where the attendees can help drive the schedule – like a conference done in the spirit of Digg. For more info check out Laura Czajkowski’s blog post and if you want to keep up to date with further details you can track things on ossbarcamp on twitter.
Archive for the ‘Ubuntu’ Category
3 Cheers for OSS Barcamp Dublin!
Sunday, November 23rd, 2008Recording Sound in Kubuntu 8.10 (running KDE 4.1)
Sunday, September 14th, 2008Exciting times ahoy! This weeks mystery was to get sound recording with the minimum of fuss. We’re not sure what soundcard is running inside the Dell Inspiron 1520 which was our test laptop but it seems to report itself as an HDA Intel SigmaTel STAC9205 in the system settings. Anyway, the first thing to do was to apt install audacity which can then be used for testing the recording functionality. Not being sure if the laptops builtin in mic had been detected correctly, we jacked in an external microphone into the mic socket.
This didn’t produce any encouraging results initially when we tried recording in audacity so we opened up the KDE volume controls by clicking the speaker icon on the taskbar and electing to open the mixer. Unfortunately the GUI controls for the mixer doesn’t have the full complement of volume controls so it was the good ol command line to the rescue – typing alsamixer in terminal brings up a nice range of controls. You can navigate between screens of controls with the tab key and jump from control to control using the left/right arrow keys. The trick was to navigate to the two controls marked ‘Capture’ and bump up the volume (they also need to be activated by pressing the spacebar when you’re on the control). Additionally, there were two controls marked ‘Digital’. One of these controlled the volume of the mic (via the up and down arrows) and the other switched between analog and digital mode (again via the up and down arrows). We found that the latter had to be set to ‘Analog I’ for the best result.
Then it was back to audacity to record a bit of chatter – and then lament how weird ones voice sounds when recorded! Now get mixing mon amis!
QUICK UPDATE (14 Sep 08)
One issue that occurred was that after recording a sample, it couldn’t be played back(“Error while opening sound device. Please check the output device settings and the project sample rate.”). Additionally, a second track couldn’t be recorded. The solution to these problems was to open the Preferences dialog and set both the Playback and Record devices to ALSA (default). Reference: http://audacityteam.org/forum/viewtopic.php?f=18&t=3377
Getting Ruby Plasmoids up and running in KDE 4.1 (on Kubuntu)
Saturday, August 2nd, 2008NOTE: THIS ARTICLE IS NOT YET COMPLETE. IF YOU FOLLOW IT THEN YOU WILL GO A LONG WAY BUT THE PLASMOID IS NOT YET DISPLAYING. SEE THE ‘Run your applet’ SECTION NEAR THE END OF THIS ARTICLE BEFORE PROCEEDING.
Introduction
KDE 4.1 is an absolutely terrific release of the KDE desktop, licking most of the issues presented in the original 4.0 release. Although it is still an early adopter release, 4.1 will be of interest to techie’s who want to get their mitts on a sexy new graphical interface and is reasonably stable for daily usage. Not quite ready for Aunt Tillie yet though! One of the nicest features is the beauty and simplicity of Plasmoids and these super flexible little gadgets can now be written in Ruby – well almost!
This guide assumes that you’re using Kubuntu Hardy Heron. But you should be able to adjust the instructions for any distro.
- The starting point for our tour is to have Ruby installed. Google this if you’re unsure as to whether or not it’s installed.
- We need to install cmake via ’sudo aptitude install cmake’. This is a cross-platform build system, similar to make.
- It’s likely that you will need to install the build UNIX build tools via ‘aptitude search build-essential’.
Get coding!
And now you’re be ready to go. The main tutorial out there on Ruby Plasmoids at time of writing is the Ruby Applet tutorial on KDE Techbase. This is a very good, well written guide on creating a simple Ruby applet in which a web browser is embeded inside the plasmoid. But the guide has a couple of gotcha’s, especially for the newbie (myself included!), so we have listed solutions to these problems as we go. In summary, use our article as an supplement to KDE Techbase’s.
Ok, to start with a demo everyone wants a nicely packaged directory of files, so let’s quickly put together the basic directory structure for our plasmoid – it’s pretty simple!
- Create a directory called ‘ruby-web-applet’
- Save the files plasma-ruby-applet-web.desktop and web_applet.rb into this directory.
- Create a file called CMakeLists.txt under your ruby-web-applet directory and paste the following code into it
set(SERVICES_INSTALL_DIR /usr/lib/kde4/share/kde4/services/)
set(DATA_INSTALL_DIR /usr/lib/kde4/share/kde4/apps/)
FIND_PACKAGE (Ruby REQUIRED)
include_directories( ${RUBY_INCLUDE_PATH} )
install(FILES plasma-ruby-applet-web.desktop DESTINATION ${SERVICES_INSTALL_DIR})
install(FILES web_applet.rb DESTINATION ${DATA_INSTALL_DIR}/plasma_ruby_web_applet)
Go to KDE Techbase
Once you have the above directory in place, go and read the Ruby Applet tutorial on KDE Techbase article down to just before the ‘Install and test the Applet’ paragraph. This will teach you what’s going on in the code. At that point come back to me as I’ll go into a little more detail on the final installation procedure!
You’re back!
Great! Ok, so we have the files on disk, you have a good idea of what the code is doing, now let’s install it and kick your plasmoid into action!
Open the CMakeLists.txt file listed above in a text editor. Change the path listed for KDE4 services and data directories to the ones on your system. These are the lines to change.
set(SERVICES_INSTALL_DIR /usr/lib/kde4/share/kde4/services/) set(DATA_INSTALL_DIR /usr/lib/kde4/share/kde4/apps/)
Do this by replacing ‘/usr/lib/kde4/share/kde4/services/’ with the output of the command ‘kde4-config –install services’ and replace ‘/usr/lib/kde4/share/kde4/apps/’ with the output of the command ‘kde4-config –install data’ command. If you are using Kubuntu then they should be the same as mine but otherwise you may need to change them.
Then make sure you are inside your ruby-web-applet directory and type
cmake .
to generate nice makefiles for you which the make command can then use. Don’t forget the trailing dot! Now type ‘make’ and ’sudo make install’. This will install your plasmoid code into the KDE4 services directory (you can see where this is by running ‘kde4-config –install services’) and your plasmoid data into the KDE4 data directory (you can see where this is by running ‘kde4-config –install data’). Effectively, the installation just involves the two files – plasma-ruby-applet-web.desktop web_applet.rb. If it’s worked then you’ll get output like
Install the project…
– Install configuration: “”
– Installing: /usr/lib/kde4/share/kde4/services/plasma-ruby-applet-web.desktop
– Installing: /usr/lib/kde4/share/kde4/apps/plasma_ruby_web_applet/web_applet.rb
The applet is now installed!
Run your applet (THIS DOES NOT WORK YET)
There are two ways to do this. In a developer kind of way you can run ‘kbuildsycoca4′ from the command line followed by ‘plasmoidviewer plasma-ruby-web-applet’. Unfortunately this currently brings up the error
findServiceByDesktopPath: not found findServiceByDesktopPath: not found
IF YOU HAVE A SOLUTION TO THIS THEN PLEASE COMMENT BELOW!!!
As a user, the cmake/make/make install procedure should have done all the necessary to install your plasmoid and you can activate it by going to the right of the task bar and clicking the Add Widgets icon. You should see your plasmoid listed but unfortunately this is not yet working – presumably for the same reason as the above. Oh well, I’m sure a solution will soon be posted. Until then, happy hackin!
Final notes
Note that the KDE techbase article provides a version of this file but it didn’t work for me because
- I knew nothing about cmake or cmake files and I didn’t even cop that right clicking on the CMakeLists.txt file link in their article and saving it to disk would also save a load of HTML into the file
- The line ‘FIND_PACKAGE (RUBY REQUIRED)’ should really be ‘FIND_PACKAGE (Ruby REQUIRED)’ as it’s case sensitive and will otherwise give you the error
CMake Error at CMakeLists.txt:6 (FIND_PACKAGE):
find_package could not find module FindRUBY.cmake or a configuration file for package RUBY.Adjust CMAKE_MODULE_PATH to find FindRUBY.cmake or set RUBY_DIR to the directory containing a CMake configuration file for RUBY. The file will have one of the following names:
RUBYConfig.cmake
ruby-config.cmake - The destination targets specified in the file didn’t work for me. Perhaps some environment variables need to be set somewhere
- I didn’t even know how to use cmake! Or that you needed to follow it up with ‘make’. Anyway we’ll come cover this soon!
I didn’t need to set any CMAKE_MODULE_PATH but if you are having troubles with this then it’s at /usr/share/cmake-2.6/Modules/ on Kubuntu Hardy Heron. You may be able to set it in your script if your having difficulties as follows ’set(CMAKE_MODULE_PATH /usr/share/cmake-2.6/Modules/)’. Again I haven’t tried this my self!
Uninitialized Constant GemRunner Error When Using Ruby Gem
Sunday, December 9th, 2007Here’s the problem…
me@host:~$ sudo gem update
/usr/bin/gem:23: uninitialized constant Gem::GemRunner (NameError)
… which had us on the ropes more than on the rails for a while. Unusually googl’ing on this error provided no solutions.
What led to the situation was that we used the source install of rubygems on Ubuntu Gutsy (7.10) instead of using the rubygems in Ubuntu’s repository but then changed our mind and apt-getted the Ubuntu repository version. Surprise! Surprise! These 2 versions were conflicting a bit; leading to the above error. The workaround is pretty simple, just go to your /usr/local/lib section and delete the site_ruby directory (as this is the remnant of the rubygems source install and thus cause of the problem). This removes all the gems (that were downloaded by the original rubygems which we no longer want) off our system. Perhaps you want to simply move this directory first in case something goes wrong and you need to revert (eg. sudo mv /usr/local/lib/site_ruby /usr_local/lib/site_ruby_old).
Note: In case your not aware, /usr/local/* is the set of directories under which programs that you compile yourself get installed to by default. Generally the directories will start out pretty empty on a freshly installed Linux distro and then as you (if ever!) compile and install programs from source (eg. using ./configure && make && make install) then they end up under this directory. Also not that programs installed using apt-get (or via rpms on non-Debian systems) don’t get put here – they usually end up under the /usr/ directory itself (this varies a bit from distro to distro but what we’ve just outlined holds true for Ubuntu anyway).
Now, once your finished you should find that gem works. Do a ‘gem list’ and see if the above error is gone. If this doesn’t work you may need to ’sudo apt-get install rubygems’. Next up, we need to rebuild that gem directory that we deleted (site_ruby) with the apt-gotten rubygems (if apt-gotten is a real word!). To do this run
’sudo gem update’
’sudo gem update –system’
You will notice that the result of these commands means that /usr/local/lib/site_ruby is back and populated. This is where ruby likes to put it’s gem extensions. Finally reinstall rails with
’sudo gem install rails’
Hope this solution works for you! We’re still getting to grips with this rails stuff so if you find any glaring errors in this post please comment below to let us know.
