Looking Inside Mac OS X

Inside Apple computers for the past few years is an operating system referred to as Mac OS X . You might also hear Mac OS X referred to as Jaguar , Panther , or Tiger (or Leopard , which is expected at the end of 2006). Like Linux, OS X has a free UNIX-like operating system at its core that, in this case, has been turned into a commercial product. That core , instead of being a Linux kernel, was based on a BSD-derivative open source project called Darwin ( www.opendarwin.org ).

Although Mac OS X and Linux are very different on the surface, there are many striking similarities. If you open a Terminal (shell) window on your Mac, you'll find that you can use many of the same basic commands that you can use from Linux. In addition, many of the same open source projects are included in both operating systems. These include:

• Samba ( Windows file/printer server)

• Apache (Web server)

• CUPS (Linux print service)

• Sendmail (mail transport agent)

• BIND (DNS server)

There are also a few differences:

• Fedora is primarily covered under the General Public License, while OS X is based partly on an Open Source license and partly on a proprietary license. In August, 2003, APSL 2.0 was released ( www.opensource.apple.com/apsl ) and is now certified as a Free Software License from the Free Software Foundation.

• Fedora uses the Linux kernel; Mac OS X is based on a Mach micro-kernel surrounded by FreeBSD services. (Apple refers to this kernel as XNU and and released it as a component of the Darwin open source operating system.)

• Most configuration in Fedora and RHEL is done using system-config windows, which often create text-based configuration files (mostly in the /etc directory) from command-line or GUI applications; Mac OS X stores the configuration file in its own NetInfo database, which is manipulated primarily by GUI tools as well as by the niutil command.

• Fedora requires root permission for many administrative operations; OS X discourages overuse of the root login and encourages user accounts that are granted administrative privileges.

For the examples in this chapter, I originally used an iMac running Mac OS X 10.3.9 (Panther), although the later 10.4 (Tiger) is also available. For this latest edition of the book, I checked the text against Mac OS X version 10.4.7, running on an Intel-based Mac Mini.

Because there were big improvements made after 10.1, I recommend that you upgrade your software if you are using 10.1. To see what version is installed on your Mac, choose About This Mac from the Apple menu on your Mac computer.