root user access in unix
To access root user privileges in Unix,
sudo su
## prompts for password and grants access
sudo su -
## switch as root user without password
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Adobe flash player installation in ubuntu chromium browser
For Chromium browser versions greater than 34, to use flash one must install Pepper flash.
For Ubuntu 14.04 or newer, run
sudo apt-get install pepperflashplugin-nonfree
sudo update-pepperflashplugin-nonfree --status
# to see what version of...
include and extend in ruby
The extend method will mix a module’s methods at the class level.
On the other hand, the include method will mix a module’s methods at the instance level, meaning the methods will become instance methods of the class.
module Stringify
# R...
Adobe flash player installation in Ubuntu
This is to install adobe flash player in Ubuntu 14.04 or higher. This works for Firefox browser.
If you have a 32-bit OS, run
sudo apt-get update
sudo apt-get install flashplugin-installer
Make sure each of the commands executed success...
Isues w/ caching in Incognito mode
I've noticed that Incognito mode retain cache from the previous session, it just don't collect any new cache while in incognito.
I usually clear the cache/cookies then go into incognito, or run a different browser profile, or a different browser ...
Check if package is installed in linux
To check if a given package is installed in Debian / Ubuntu, type
dpkg -s <package-name>
To get a neater output use dpkg-query which accepts wildcards as well.
dpkg-query -l <package-name>
In Redhat / Fedora / CentOS use the foll...
difference between attr_accessor and initialize
attr_accessor is used to create setter and getter methods for instance variables so that they can be accessed outside the class. initialize is the special method in ruby that gets called when an object is instantiated.
class Birthday
attr_ac...
calling super in initialize
class Person
def initialize(name)
@name = name
end
end
class Employee < Person
end
emp = Employee.new # throws error wrong number of arguments
emp = Employee.new("foo") # parent class initialize method is called
cla...
Class_eval and Instance_eval
class_eval is called on a class object and is used to create instance methods for the class at runtime.
%w(administrator developer teamlead tester).each do |user|
class_eval <<-EOR
def is_#{user}?
site == "MYACCOUNT_#{org.upcase}" ...
listing methods of class and object (instance)
class Myclass
def one
puts "one is called"
end
end
ss = Myclass.new
puts Myclass.methods
# returns array of methods for the class. Includes both class and instance methods and methods inherited from parents.
puts Myclass.instanc...
Abstract classes in rails
class AbstractModel < ActiveRecord::Base
self.abstract_class = true
end
class Foo < AbstractModel
end
class Bar < AbstractModel
end
Foo and Bar both inherit properties and methods of the Abstract Model while being in separate tables...