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
is control-D . The above is just for UNIX. If you're using DOS, try this:
- ^D
- 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
with
- foo
in all C source and header files in the current working directory, backing up the original files with ".bak" appended:
- bar
- % ruby -i.bak -pe 'sub "foo", "bar"' *.[ch]
This program works like the UNIX
command (but works slower than
- cat
):
- cat
- % ruby -pe 0 file
