How does MacPorts install packages? How can I activate a Ruby installation done via MacPorts?

Question

After trying to install ruby19 on my machine (PPC, Mac OSX 10.5.7) using the following commandline

sudo port install ruby19

the version of

Answer 1

Just a quick clarification about MacPorts. Ayaz is right that, by default, MacPorts will install things in /opt/local. (This makes it easy to globally uninstall later, if you want, and it keeps MacPorts packages out of the way of OS X packages.)

When you install MacPorts, it will normally edit your $PATH (and your $MANPATH) for you by updating your user's .profile (creating it, if it doesn't already exist).

As a precaution, the installer will create a backup of the original .profile in case you want to roll back the changes (or if you completely uninstall MacPorts later). Here's an example from a random machine at work.

admin ~ $ ls .profile*
.profile  .profile.macports-saved_2009-08-03_at_14:55:56

If you look in .profile you should see something like this:

##
# Your previous /Users/admin/.profile file was backed up as /Users/admin/.profile.macports-saved_2009-08-03_at_14:55:56
##

# MacPorts Installer addition on 2009-08-03_at_14:55:56: adding an appropriate PATH variable for use with MacPorts.
export PATH=/opt/local/bin:/opt/local/sbin:$PATH
# Finished adapting your PATH environment variable for use with MacPorts.

# MacPorts Installer addition on 2009-08-03_at_14:55:56: adding an appropriate MANPATH variable for use with MacPorts.
export MANPATH=/opt/local/share/man:$MANPATH
# Finished adapting your MANPATH environment variable for use with MacPorts.

If your $PATH hasn't been updated, you should adjust it, since otherwise, you will have trouble using the port tool and the software you install via MacPorts.