Change the name of your Ubuntu machine
In order to rename your Ubuntu box, replace all occurences of the the old name in the following two files:
/etc/hostname/etc/hosts
After a reboot your hostname is changed. If you don't want to reboot your Ubuntu box you have to execute hostname your.hostname.
Related cards:
How to get the hostname of the current machine in Rails or a Ruby script
Use Socket.gethostname. So for a machine whose hostname is "happycat", it will look like this:
>> Socket.gethostname
=> "happycat"
That should work right away for your Rails application. For plain Ruby, you first need to do:
requi...
Show the name and version of your Linux distribution
To list the name and version of your Linux distribution, type the following:
cat /etc/*-release
The Ruby Object Model
In Ruby (almost) everything is an Object. While this enables a lot of powerful features, this concept might be confusing for developers who have been programming in more static languages, such as Java or C#. This card should help understanding t...
How to make changes to a Ruby gem (as a Rails developer)
At makandra, we've built a few gems over the years. Some of these are quite popular: spreewald (> 1M downloads), active_type (> 1M downloads), and geordi (> 200k downloads)
Developing a Ruby gem is different from developing Rails applications, w...
How to resize your boot partition when there is an encrypted partition after it
Boot partitions from installations prior to the 16.04 era are terribly small. When you install updates and encounter errors due to a full /boot partition, consider risizing it.
If you can't do the steps described below, ask someone experienced ...
RSpec: Leverage the power of Capybara Finders and Matchers for view specs
View specs are a powerful tool to test several rendering paths by their cases instead of using a more costing feature spec. This is especially useful because they become quite co...
How to install a current version of git to your Ubuntu machine
As described by the linked Stackoverflow answer, run these commands:
sudo add-apt-repository ppa:git-core/ppa -y
sudo apt-get update
sudo apt-get install git
git --version
This will get you Git 2.6.4 (as of Dec 2015).
Troubleshooting...
CSS: Matching against attributes and their values (or parts of them)
You probably know that you can use CSS selectors to match against elements and their attributes, such as:
a[title] { /* any <a> that has a "title" */ }
a[data-fancy="true"] { /* any <a> that has their "data-fancy" attribute set to "true" *...
How to change the locale of a PostgreSQL cluster
There may be reasons to change the locale of your Postgres cluster. A popular one is your development system's locale being used by default (which may be annoying). Here is how to do that.
Beware: By following the steps below, you will drop and r...
How to change the hostname in Cucumber features
Capybara uses www.example.com as the default hostname when making requests.
If your application does something specific on certain hostnames and you want to test this in a feature, you need to tell Capybara to assume a different host.
Given...