#!/usr/bin/ruby -w

puts "Hello, Ruby!";

Here, we assumed that you have Ruby interpreter available in /usr/bin directory. Now, try to run this program as follows −

$ ruby test.rb

This will produce the following result −

Hello, Ruby!

You have seen a simple Ruby program, now let us see a few basic concepts related to Ruby Syntax.

Whitespace in Ruby Program

Whitespace characters such as spaces and tabs are generally ignored in Ruby code, except when they appear in strings. Sometimes, however, they are used to interpret ambiguous statements. Interpretations of this sort produce warnings when the -w option is enabled.

Example

a + b is interpreted as a+b ( Here a is a local variable)
a  +b is interpreted as a(+b) ( Here a is a method call)

Line Endings in Ruby Program

Ruby interprets semicolons and newline characters as the ending of a statement. However, if Ruby encounters operators, such as +, −, or backslash at the end of a line, they indicate the continuation of a statement.

Ruby Identifiers

Identifiers are names of variables, constants, and methods. Ruby identifiers are case sensitive. It means Ram and RAM are two different identifiers in Ruby.

Ruby identifier names may consist of alphanumeric characters and the underscore character ( _ ).

Reserved Words

The following list shows the reserved words in Ruby. These reserved words may not be used as constant or variable names. They can, however, be used as method names.

Here Document in Ruby

“Here Document” refers to build strings from multiple lines. Following a << you can specify a string or an identifier to terminate the string literal, and all lines following the current line up to the terminator are the value of the string.

If the terminator is quoted, the type of quotes determines the type of the line-oriented string literal. Notice there must be no space between << and the terminator.

Here are different examples −

#!/usr/bin/ruby -w

print <<EOF
   This is the first way of creating
   here document ie. multiple line string.
EOF

print <<"EOF";                # same as above
   This is the second way of creating
   here document ie. multiple line string.
EOF

print <<`EOC`                 # execute commands
	echo hi there
	echo lo there
EOC

print <<"foo", <<"bar"  # you can stack them
	I said foo.
foo
	I said bar.
bar

   This is the first way of creating
   her document ie. multiple line string.
   This is the second way of creating
   her document ie. multiple line string.
hi there
lo there
      I said foo.
      I said bar.

BEGIN {
   code
}

#!/usr/bin/ruby

puts "This is main Ruby Program"

BEGIN {
   puts "Initializing Ruby Program"
}

Initializing Ruby Program
This is main Ruby Program

END {
   code
}

#!/usr/bin/ruby

puts "This is main Ruby Program"

END {
   puts "Terminating Ruby Program"
}
BEGIN {
   puts "Initializing Ruby Program"
}

Initializing Ruby Program
This is main Ruby Program
Terminating Ruby Program

# I am a comment. Just ignore me.

name = "Madisetti" # This is again comment

# This is a comment.
# This is a comment, too.
# This is a comment, too.
# I said that already.

=begin
This is a comment.
This is a comment, too.
This is a comment, too.
I said that already.
=end