From: Timothy Hunter <TimHunter@...>
Date: 2007-01-22T03:27:12+09:00
Subject: Re: uninstalling the mac tiger version of ruby

libsfan01 wrote:
>> You'll probably get "ruby 1.8.5"
>>
>>     
>
> Yes it seems to be the case that its looking for the wrong version.
> timothy how can i change the setting of the path variable so that the
> latest version is accessed? (from "usr/bin/ruby" to
> "usr/local/bin/ruby")?
>
> thanks
>
> marc
>
>   

PATH is an environment variable that the bash shell uses when it 
searches for a command. In bash you set environment variables like this:

export VAR=value

Notice there's no leading $ in the name when it's on the left-hand side 
of the assignment. When you want to get the value of an environment 
variable you precede its name with a $. Now, you want to prepend 
/usr/local/bin to the current value of PATH. Enter this command:

echo $PATH

This will show you the current value of PATH. Then enter:

export PATH=/usr/local/bin:$PATH

(Directories in the PATH are separated by colons.) issue "echo $PATH" 
again to ensure that the change worked.

Now enter "ruby -v". You should see "ruby 1.8.5" because OS X found ruby 
in /usr/local/bin.

Of course you don't want to have to redefine your PATH variable every 
time you open a terminal. To get your PATH set the way you want it every 
time you can add this command to a bash configuration script. The bash 
shell gets its configuration from a number of scripts. I believe the 
preferred one for this sort of thing is .bash_profile. The bash shell 
looks for this file in your home directory. You may already have such a 
file. If so, save a backup copy, open it in a text editor and add the 
command on a separate line. If the file doesn't already exist, create it 
and add these two lines:

#! /bin/bash
export PATH=/usr/local/bin:$PATH

Save the file, close the terminal window and open a new one. Issue "echo 
$PATH" again to see your changed PATH. Issue "ruby -v" and ensure that 
you're getting "ruby 1.8.5".

Warning: be careful. If you screw up your path many things in OS X will 
stop working. If you encounter problems (like commands not working) just 
delete your .bash_profile (or restore it to its previous state) and try 
again. Always close the terminal window and open a new window after 
making a change.

For more info search for bash on the web or issue the "man bash" command 
in a terminal window.