I was trying to install Meld ad git diff tool. I saw this article for installation How to install Mend on MAC OS. It says that first install fink. Can anybody tell me what is this all about? I tried there site and the only think I understood is that I will be able to run unix open source softwares on Mac. But I am not clear about it. I thought mac is based on Unix and you can run most of the stuff on mac that you can on unix.
Fink appears to be a package manager for OS X in much the same way as aptitude is for Debian and YUM is for Fedora, for example. The idea is that once you have fink installed you just ask fink to install meld and it goes and retrieves all the required packages and installs them on your Mac.
There are a number of systems like this available for Mac, my particular favourite being Homebrew. Another widely used one is MacPorts which I didn't like that much but I guarantee somebody will disagree with me. It's pretty popular too.
I haven't used either Fink or MacPorts, but I just started using HomeBrew, and it was very easy to get started with. (Tiny hiccup: it needs bash to run, whereas I was using tcsh. Figuring that out took about 30 seconds.)
But then I was able to install some libraries required to compile PovRay, and that took a fraction of the time I had spent a few days earlier trying to install those libraries manually. Now I'm totally sold on HomeBrew.
Word of caution on using these tools. There are OSX updates that can break things you have installed using these tools. These tools install libraries and application that have no OSX binary so they are often times compiled during installation using other libraries that weren't originally build for OSX. So when OSX updates, some of the dependencies can change and then you have to reinstall the broken libraries / applications.
I haven't ran into this often, but it has never been pleasant for me when it does happen.