String Interpolation in Ruby

To display the contents of a variable using puts, use the syntax

#{variable_to_display}

For example, to if x=5, to display "The value of X is 5", do: 

x=5
puts "The value of X is #{x}"  

To test this, save the above two lines to a file called string_interp.rb  and then do

 ruby string_interp.rb  

Building Shoes in Linux

Shoes is a lightweight GUI toolkit for Ruby, website here. I couldn't get the download working, so built it from source using the instructions here.

A couple of notes - I built against Ruby 1.9.3 (this doesn't appear to have been updated in the Wiki instructions yet). Also, if you want to rebuild from source more than once, you have to do a

 rake clean  

before executing

 rake  

a second time.

Installing Rails 3.2 into Linux Mint (and other Linux distributions)

1) Install RVM:

  bash -s stable < <(curl -s https://raw.github.com/wayneeseguin/rvm/master/binscripts/rvm-installer)   

2) Install or update RubyGems:

 gem update --system  

3) Install Rails:

 gem install rails  

That's it! Any problems, let me know below.

RVM Installation Problems in Linux Mint

I was having problems installing RVM into Linux Mint, it seems that somehow RVM is/was broken for Ubuntu distros. I was having issues with RVM saying that it couldn't fetch the ruby source, and curl errors as well. Purging and reinstalling RVM:

Remove RVM:

 sudo apt-get --purge remove ruby-rvm  
 sudo rm -rf /usr/share/ruby-rvm /etc/rvmrc /etc/profile.d/rvm.sh  

Close terminal window and open a new one then reinstall RVM with:

 bash -s stable < <(curl -s https://raw.github.com/wayneeseguin/rvm/master/binscripts/rvm-installer)  

as per this StackOverflow answer solved my problems.

Changing the Primary Monitor in Linux Mint, and Persisting the Change

In a previous post, I explained how to switch the primary monitor in Linux Mint, using a small script. This change however, does not persist when you reboot your machine. If you haven't already, take a look at that post, as you will need to run the script to get the names of your monitors, which are required for this example.


To make the primary monitor change permanent, go to Menu -> Other -> Startup Applications, and click Add. Give the startup program a name, like "Set Primary Monitor", then in the Command box, enter:

 xrandr --output monitorName --primary  

where monitorName is the name of the monitor you wish to use as the primary monitor, as listed in the script from this post. My command for example, looked like this:

 xrandr --output DVI-I-2 --primary  

Your Add Startup Program window should look something like this:

Click Add, and you're done! Let me know if this works for you below!

Changing the primary monitor in Linux Mint (and other distributions)

*** Update: To persist this change between machine restarts, see this post ***


1) Save this script as monitor-switcher.sh:

 #!/bin/bash  
 # Author: Andrew Martin  
 # Credit: http://ubuntuforums.org/showthread.php?t=1309247  
 echo "Enter the primary display from the following:"               # prompt for the display  
 xrandr --prop | grep "[^dis]connected" | cut --delimiter=" " -f1     # query connected monitors  
 read choice                                        # read the users's choice of monitor  
 xrandr --output $choice --primary                         # set the primary monitor  

2) Make executable with:

 chmod +x monitor-switcher.sh  

3) Execute by typing:

 ./monitor-switcher.sh  

4) Enter the name of the monitor you want to be the primary monitor.


All credit to the article here.

Installing the ADT Plugin for Eclipse under Linux Mint

If you get the following error when trying to install the ADT plugin for Eclipse:

Cannot complete the install because one or more required items could not be found.

Software being installed: Android Development Tools 16.0.1.v201112150204-238534 (com.android.ide.eclipse.adt.feature.group 16.0.1.v201112150204-238534)

Missing requirement: Android Development Tools 16.0.1.v201112150204-238534 (com.android.ide.eclipse.adt.feature.group 16.0.1.v201112150204-238534) requires 'org.eclipse.wst.sse.core 0.0.0' but it could not be found

You need to install linux-tools first. Go to Help -> Install New Software, and enter http://download.eclipse.org/technology/linuxtools/update into the Work with box. Install all of the components that appear, then restart Eclipse when prompted. Now go back to Help -> Install New Software, and enter
https://dl-ssl.google.com/android/eclipse/ into the Work with box. Go through the installation procedure again and the ADT Plugin will install successfully.