Running ruby


In the past, I always tested some ruby statements with irb. Now I can test a small ruby program in the following way.

[monkey@itlodge octopress]$ ruby
str = "abc"
puts str

After hit ruby, it allows me to type as many code as possible.Finally, press Ctrl+d will end the input and it will evaluate the code.


When writing a script, we always use #! and specific which language used to run the code.This is the Unix Shebang notation.For example:

#!/usr/bin/ruby -w
puts "abc"

From the man page, I know that the -w option means Enables verbose mode without printing version message at the beginning.

But, many guys like this style:

#!/usr/bin/env ruby
puts "abc"

From the man page, I know that the env is a program that run a program in a modified environment.So it can search the $PATH and find the ruby program to run.

Ruby documentation

The site contains a complete set of the RDoc documentation for Ruby.

The ri tool is very useful for looking up documentation.If you want to find the documentation for a class, just type ri ClassName. For example:

[monkey@itlodge ~]$ ri Vector
= Vector < Object

= Includes:
Enumerable (from ruby core)

(from ruby core)
The Vector class represents a mathematical vector, which is useful in its own
right, and also constitutes a row or column of a Matrix.

== Method Catalogue

To create a Vector:
*   Vector.[](*array)                   
*   Vector.elements(array, copy = true) 

To access elements:
*   [](i)                               

To enumerate the elements:
*  #each2(v)                            
*  #collect2(v)                         

If you want to find the documentation for a method, just type ri method's name.For example:

[monkey@itlodge ~]$ ri sleep
= .sleep

(from ruby core)
=== Implementation from Kernel
  sleep([duration])    -> fixnum


Suspends the current thread for duration seconds (which may be
any number, including a Float with fractional seconds). Returns the actual
number of seconds slept (rounded), which may be less than that asked for if
another thread calls Thread#run. Called without an argument, sleep() will
sleep forever.    #=> 2008-03-08 19:56:19 +0900
  sleep 1.2   #=> 1    #=> 2008-03-08 19:56:20 +0900
  sleep 1.9   #=> 2    #=> 2008-03-08 19:56:22 +0900


A method’s name may be the same in different classes or modules.In this case, ri will list all of them.If you type ri ClassName.method's name, it will show only the documentation of the corresponding class’s.

More contributions, more reputations.If a class or module hasn’t yet documented in RDoc, send an email to to ask them to add.