Ruby Document Center-Learning to start _ruby topics

First, you have to check if Ruby is installed. In the shell prompt entered prompt (here is expressed as "%", so don't typing%), typing

% Ruby-v


(-V tells the interpreter to print out Ruby version) and then knocks in the carriage. If Ruby is installed, you will see a message similar to the following:

% Ruby-v
Ruby 1.6.6 (2001-12-26) [I586-linux]


If Ruby is not installed, you can have the administrator install it, or you can do it yourself, Ruby is a free software that does not have the installation or use restrictions.

Now, let's play with Ruby. You can place a Ruby program directly on the command line with an-e argument:

% ruby-e ' print ' Hello world\n '
Hello World


In general, Ruby programs are saved in a file.

% Cat > Test.rb
print "Hello world\n"
^d
% Cat TEST.RB
print "Hello world\n"
% Ruby Test.rb
Hello World


^d refers to control-d. Above is the case under UNIX. If you use DOS, that's it:

c:\ruby> Copy con:test.rb
print "Hello world\n"
^z
C:\ruby> type TEST.RB
print "Hello world\n"
C:\ruby> Ruby Test.rb
Hello World


When writing more practical code than this, you will want to use a real text editor!

Something incredibly complex and useful can be done with a single line of commands. For example, this gadget replaces Foo in all C-source programs and header files in the current directory with bar and appends the original file with a ". Bak" Backup:

% Ruby-i.bak-pe ' Sub ' foo ', ' Bar ' ' *. [CH]


This program is similar to the Cat command under UNIX (but slower than cat):

% Ruby-pe 0 File