Error codes on install.ish file to Terminal

[Heathyr Millard]

Hi all. I am trying to run REfind on a late 2006 iMac, so that I can load Ubuntu on an already existing partition I created for it, when I input the install.ish file to terminal on main partition, I am met with this message instead :
*Last login: Wed Oct 14 22:57:45 on console
heathyrs-imac:~ BatGirl$ /Users/BatGirl/Downloads/refind-bin-0.9.2/install.sh
Not running as root; attempting to elevate privileges via sudo....

*WARNING: Improper use of the sudo command could lead to data loss
or the deletion of important system files. Please double-check your
typing when using sudo. Type "man sudo" for more information.

To proceed, enter your password, or type Ctrl-C to abort.

*I know nothing about the command prompt for Macs, so I am not sure what this means. I aborted the terminal action. Help?

[Roderick W. Smith]

That's normal. The install.sh script needs administrative access to install itself. In OS X, this is normally granted by preceding a command with sudo. If you try to run install.sh without this, it tries to acquire these privileges itself. The "Improper use of the sudo command..." warning is part of Apple's sudo implementation. IIRC, it appears the first time you use sudo and then doesn't appear in subsequent uses. The message sounds scary, but what you're doing is, in principle, no more (or less) risky than typing your password when you run a backup utility, install a program via a .pkg file, or do other things that create a GUI prompt for your password.

[Heathyr Millard]

ok so I can go ahead and run it without hesitation? I am very new to all this! I just want to make sure I'm doing everything properly

[Heathyr Millard]

ok, I installed it successfully onto my main partition. I am a little confused at what next, Ubuntu did not load, it said no mountable file system

[Roderick W. Smith]

When you reboot, rEFInd should appear and give you boot options. I suspect you've gotten that far, but you're saying that Ubuntu then failed to start, and complained about the lack of mountable file systems. Do you remember if you created a separate /boot partition for Ubuntu? If so, you must highlight the Ubuntu option in rEFInd, hit F2 or Insert twice, and add "ro root={something}" to the command line, where "{something}" is a description of your Ubuntu root partition, like "/dev/sda5" or "/dev/mapper/ubuntu-root". Once you boot Ubuntu, you can run the mkrlconf.sh script that came with rEFInd to create a configuration file that will obviate the need for this step in the future. If you're not sure what your root device is, show use your partition table (the output of sudo parted /dev/sda print in an Ubuntu live CD's Terminal or diskutil list in OS X's Terminal).

If this is not the problem, then we need more information. Taking a digital photo of the screen with the error message and posting it may help.