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Ruby user's guide | Getting started |
First, you'll want to check whether ruby is installed. From
the shell prompt (we denote a shell prompt by "%
", so
you should not type the "% 
"), type
% ruby -v
(-v
tells the interpreter to print the version of ruby),
then press the Enter key. If ruby is installed, you will
see a message something like the following:
% ruby -v ruby 1.6.1 (2000-09-27) [i586-linux]
If ruby is not installed, you can ask your administrator to install it, or you can do it yourself, since ruby is free software with no restrictions on its installation or use.
Now, let's play with ruby. You can place a ruby program
directly on the command line using the -e
option:
% ruby -e 'print "hello world\n"' hello world
More conventionally, a ruby program can be stored in a file.
% cat > test.rb print "hello world\n" ^D % cat test.rb print "hello world\n" % ruby test.rb hello world
^D
is control-D. The above is just for
UNIX. If you're using DOS, try this:
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 substantial code than this, you will want to use a real text editor!
Some surprisingly complex and useful things can be done with
miniature programs that fit in a command line. For example, this
one replaces foo
with bar
in all C source
and header files in the current working directory, backing up the
original files with ".bak" appended:
% ruby -i.bak -pe 'sub "foo", "bar"' *.[ch]
This program works like the UNIX cat
command (but is
slower than cat
):
% ruby -pe 0 file
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