First, you'll want to check whether ruby is installed. From the shell prompt (denoted here by "
%", so don't 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 1.6.6 (2001-12-26) [i586-linux]
If ruby is not installed, you need to install it, 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
^Dis 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
foowith
barin 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
catcommand (but works slower than
cat):
% ruby -pe 0 file
