TweetFollow Us on Twitter

Why MkLinux?

Volume Number: 13 (1997)
Issue Number: 10
Column Tag: Tools Of The Trade

Why MkLinux?

by Rich Morin

Or, is grep really worth 500 MB of disk space?

So What Is MkLinux?

MkLinux is a port of the GNU System to the Power Macintosh. It provides a Unix-like user and programming environment, with hundreds of useful commands (software development and document preparation tools, network servers and tools, and other utilities. With very few exceptions (e.g., the boot code), all of the source code for MkLinux is freely redistributable.

The MkLinux port is based on the Linux 2.x kernel, which is used as a "single server" for the Mach 3 microkernel. Thus, the Linux kernel runs as a user-mode process, handling OS "personality" issues, while the Mach microkernel handles low-level I/O and resource allocation tasks. This two-part design has assorted benefits, including the ability to debug a new Linux server (as an application) while running the system on a older (trusted) server.

Because MkLinux has pre-emptive multitasking and runs as a "native" OS, it makes quite efficient use of the Power Macintosh hardware. A Power Mac 6100, for instance, is capable of serving as the local "unix box" for a dozen or more casual users and programmers. Aside from providing access to the normal range of unix tools, MkLinux supports a wide variety of network services, including FTP, HTTP, NFS, Telnet, and the X Window System.

Once a MkLinux system has booted, it is "just" a Linux system. That is, it has all of the standard Linux user and programming interfaces, system administration tools, etc. The big difference, however, is that MkLinux is running on an integrated hardware platform. Consequently, MkLinux system installation does not lose the administrator in a twisty maze of DMA vector and IRQ settings, jumpers, and other Intel-specific annoyances.

History and Current Status

Although MkLinux has been under development for a few years, it has only been available to the general public for a short while. Apple's first public announcement concerning MkLinux was made at the Free Software Foundation's First Conference on Freely Redistributable Software (February 1996). Since that time, Apple has issued several MkLinux Developer Releases. DR3, for instance, is expected to be available by the time you read this article.

MkLinux has never been a large-scale project for Apple Computer. Staffing has never exceeded five engineers, split between Apple and The Open Group Research Institute. The MkLinux Reference Release, although sponsored and assisted by Apple, was produced by Prime Time Freeware. Through the efforts of volunteers, large numbers of applications and drivers appear on MkLinux-related FTP sites. If Linux is the system where "everything is done by someone else", MkLinux is certainly well in line with this tradition.

The MkLinux user community is served by email lists, web sites, and other Internet-based facilities. The email lists are quite active; more than 5000 subscribers are currently registered. They handle MkLinux announcements, setup and programming issues, etc. The high signal-to-noise ratio of the lists reflects the cooperative attitude of the MkLinux community. The Apple MkLinux web site http://www.mklinux.apple.com contains announcements, news, online help, and pointers to other Internet-based resources.

Who Uses MkLinux?

The Macintosh is very popular in academia, whether in computer labs, professor's offices, or dormitory rooms. By making Linux available for the Power Macintosh, Apple allows these academic institutions (and associated individuals) to make better use of existing hardware. For instance, a computer science graduate student might write a device driver for MkLinux, then switch back to Mac OS to create the diagrams and write up a paper describing it.

As hinted above, MkLinux is also finding use as a network server. NuBus-based Power Macs are not considered very powerful by today's standards, but they perform quite well as MkLinux servers. In fact, a Power Mac 6100/60 is roughly equivalent in performance to an early Sun SparcStation 5 or a 90 MHz Pentium system. If the 6100 is already on hand (or cheaply available), it can be an economical and very convenient alternative to an Intel or Sparc-based system.

We are also starting to see quite a bit of interest from the Apple developer community. Developers have been quick to realize that MkLinux provides a very economical way to look at a Mach/unix system on the Power Macintosh. Better yet, both the source code and a large body of reference materials are available.

Apple's original motivation in sponsoring MkLinux, by the way, came from its Higher Education sales force. It seems that they got tired of hearing about the fact that Intel-based PCs were more versatile (running both Windows and Linux). So, when the MkLinux skunk works project got started, the Higher Ed folks were quick to support it.

MkLinux Basics

If you are already familiar with Intel-based Linux systems, feel free to skip down to the next section: a running MkLinux system is essentially indistinguishable from a running Intel-based Linux system. If you have used other unix-based systems, all you need to know is that (Mk)Linux provides extended versions of most traditional BSD and System V commands.

If you're still with us, you're probably wondering how much of a learning curve you're facing before you can be a productive MkLinux user and programmer. As usual, the news is mixed: the bad news is that it could take you years to learn everything about the entire system. The good news is that you can master the basics in a few hours and that you don't really need to know everything about MkLinux to be quite productive on it. So, let's get started...

Like MS-DOS, MkLinux has a command-oriented user environment. Although X Windows provides the ability to run graphical applications, it does not have the pervasive GUI-based semantics, let alone the consistent user interface guidelines, found in Mac OS. Hence, MkLinux windows tend to be "glass teletypes", used to communicate with a command line interpreter.

Unlike MS-DOS, however, MkLinux supples several command line interpreters, or "shells", along with hundreds of shell-oriented commands and "little languages". By combining these tools, either on the command line or as saved "shell scripts", you can make MkLinux do some pretty amazing things.

Let's say that one of your directories contains several hundred files, each of which contains one or more C routines. You want to look at some examples of how the routine "foo" is used, so you ask the MkLinux "grep" command to take a look:

rdm@mklinux 1: grep foo *.c
bar.c:  x = foo(...);
baz.c:  y = foodp(...);
baz.c:  z = foo(...);
...

Although the first line looks just fine, the second line shows that we weren't sufficiently precise in our search. So, we use the "-w" flag to tell grep to look for the "word" foo:

rdm@mklinux 2: grep -w foo *.c
bar.c:  x = foo(...);
baz.c:  z = foo(...);
...

There seem to be quite a lot of matching lines, however; let's just get a list of the file names:

rdm@mklinux 3: grep -lw foo *.c
bar.c
baz.c
...

How many files are there? Let's ask the MkLinux word count (wc) utility for a count:

rdm@mklinux 3: grep -lw foo *.c | wc -l
42

Now let's suppose that we want to copy all of the matching files off to a separate directory, for detailed examination and/or modification. MkLinux lets us do this very easily:

rdm@mklinux 4: mkdir hax
rdm@mklinux 5: cp `grep -lw foo *.c` hax

There are hundreds of commands in the MkLinux repertoire, yielding a staggering number of combinations. And, because sequences of commands can be saved as "shell scripts", creating new commands is a trivial process. MkLinux shells have most of the common programming constructs, including variables, control flow operators, etc. If you want more programming power, however, you can always drop into a language such as awk or perl.

The creation and (re-)use of simple commands is fundamental to the MkLinux way of doing things. Rather than try to create monolithic programs that can do every conceivable task, MkLinux programmers create small, general-purpose tools and combine them into task-specific commands and scripts.

In the example above, for instance, cp has no need to know anything about string searching and grep has no need to know anything about file copying. The combination, however, is able to do a rather powerful and specialized function (string-based file copying) with little effort.

Legal Issues

As an Apple developer, you are probably familiar with GCC, GDB, GNU Emacs, and other tools that have emerged from the GNU Project. As an implementation of the GNU System, MkLinux contains hundreds of these tools. In addition, it includes a great deal of BSD (Berkeley Software Distribution), Mach, and X Window System code. In short, MkLinux is a compilation of compilations, including a variety of software and associated legal restrictions.

Software developed by the GNU Project is (almost always) covered by the terms of the GNU General Public Licence (GPL). In addition, many programs developed by third parties (e.g., GhostScript and Perl) are also available under the GPL. Thus, if you plan to use MkLinux (or any other GNU software), a basic understanding of the GPL is advised.

The GNU GPL allows both non-commercial and commercial distribution, in either source or binary format, of materials it covers. It requires, however, that distributors of binary code make the source code economically available, upon request. It also prohibits any other restrictions (including collection copyrights) from being placed on the materials.

Thus, although you are free to examine, modify, redistribute, and use GPLed code, you are not free to turn it into proprietary code. In general, software developed using GNU tools is not affected by the GPL, save that use of libraries may "contaminate" developed code. For detailed information on the GNU Project and the GNU GPL, see the GNU web site http://www.gnu.org.

Much of the remaining freeware in the MkLinux distribution is covered by "University-style" licenses, such as those used by CMU, MIT, and UC Berkeley. These licenses require that the source code retain a notice showing its origins, but say nothing restricting the code's inclusion into commercial products.

Finally, you should expect to find a few "unique" licenses, ranging widely in both style and terms. You are on your own when dealing with these notices. Although these licenses normally allow free use within a given organization, their terms for distribution may prohibit external distribution, even for non-commercial purposes. So, be sure to read the fine print!

Porting Issues

Because MkLinux is closely based on Linux, it is able to build most Linux source archives with little trouble. The problems that do surface tend to stem from basic architectural incompatibilities such as byte ordering or the need for particular hardware. Finally, because of the Mach-based internal structure of MkLinux, Linux driver code does not port at all trivially.

Most Linux programs are written in an architecture-independent manner. At worst, they contain a few #ifdef statements. A few Linux programs, however, make assumptions about the ordering of bytes within words, etc. Because PowerPC CPUs address differently than Intel CPUs, this can cause programs to malfunction. There is also an assumption, on Intel-based platforms, that variables of type char are signed. MkLinux assumes that chars are unsigned, but a compiler option can be used to change this assumption.

If the source code comes from another variant of unix (e.g., BSD or System V), things can get a bit trickier. Although most unix system calls and library functions are standardized, each flavor of unix tends to have a few unique (or modified) interfaces. Linux is quite popular, however, so you should expect to find Linux-oriented #ifdef statements in most common freeware packages.

Porting non-trivial software from Mac OS, on the other hand, is likely to be a real challenge. The MkLinux system calls and library functions have many of the same capabilities of Mac OS routines, but their exact nature, names, and calling sequences are apt to to be very different. Be prepared to look up a lot of function definitions!

Worse, the event-driven model favored by Mac OS applications is not found in most MkLinux programs. Some window-based applications may be written in an event-driven manner, but that's about it. And, although X may look a bit like the Finder, it is a radically different environment, sharing few of the Finder's basic assumptions and rules. In short, you should treat MkLinux as a Linux system that happens to run on a Power Macintosh, rather than a weird variant of Mac OS.

MkLinux Resources

As noted above, MkLinux is well served by email lists, FTP sites, and web servers. The best starting point is Apple's MkLinux web server http://www.mklinux.apple.com. Look around this site for general information, late-breaking news, mailing lists, online help, and links to related sites. As the MkLinux community grows, volunteers will take up more and more of the burden of disseminating MkLinux-related information, but the Apple web site is likely to remain as the best starting point for any search.

The Linux community is well served by printed documentation, software collections, and online information resources. With the exception of some kernel- and hardware-related material, most of these resources are quite applicable to MkLinux. More generally, much of the unix literature is relevant to MkLinux. After all, MkLinux is basically a free version of unix.

All modesty aside, however, the definitive work on MkLinux is "MkLinux: Microkernel Linux for the Power Macintosh" (Prime Time Freeware, 1997, ISBN 1-881957-24-1, $50 MSRP). This Apple-sponsored product combines a 360-page introductory and reference manual with a MkLinux distribution CD-ROM and an HTML-basedreference CD-ROM, covering Linux, Mach, NeXT, and the Power Macintosh. For more information, visit the Prime Time Freeware web site http://www.ptf.com.


Rich Morin, rdm@ptf.com, is the editor of "MkLinux: Microkernel Linux for the Power Macintosh", published by Prime Time Freeware (http://www.ptf.com). A 30-year veteran of the computer industry, Rich writes for both SunExpert and UNIX Review magazines. His home system is a three-headed Power Macintosh 7100/80, running Mac OS. It is, however, networked to several local UNIX (MkLinux and SunOS) boxes.

 
AAPL
$116.47
Apple Inc.
+0.16
MSFT
$47.98
Microsoft Corpora
-0.72
GOOG
$537.50
Google Inc.
+2.67

MacTech Search:
Community Search:

Software Updates via MacUpdate

Cobook 3.0.7 - Intelligent address book....
Cobook Contacts is an intuitive, engaging address book. Solve the problem of contact management with Cobook Contacts and its simple interface and powerful syncing and integration possibilities.... Read more
StatsBar 1.9 - Monitor system processes...
StatsBar gives you a comprehensive and detailed analysis of the following areas of your Mac: CPU usage Memory usage Disk usage Network and bandwidth usage Battery power and health (MacBooks only)... Read more
Cyberduck 4.6 - FTP and SFTP browser. (F...
Cyberduck is a robust FTP/FTP-TLS/SFTP browser for the Mac whose lack of visual clutter and cleverly intuitive features make it easy to use. Support for external editors and system technologies such... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
Evernote 6.0.1 - Create searchable notes...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
calibre 2.11 - Complete e-library manage...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital... Read more
Herald 5.0.1 - Notification plugin for M...
Note: Versions 2.1.3 (for OS X 10.7), 3.0.6 (for OS X 10.8), and 4.0.8 (for OS X 10.9) are no longer supported by the developer. Herald is a notification plugin for Mail.app, Apple's Mac OS X email... Read more
Firetask 3.7 - Innovative task managemen...
Firetask uniquely combines the advantages of classical priority-and-due-date-based task management with GTD. Stay focused and on top of your commitments - Firetask's "Today" view shows all relevant... Read more
TechTool Pro 7.0.6 - Hard drive and syst...
TechTool Pro is now 7, and this is the most advanced version of the acclaimed Macintosh troubleshooting utility created in its 20-year history. Micromat has redeveloped TechTool Pro 7 to be fully 64... Read more
PhotoDesk 3.0.1 - Instagram client for p...
PhotoDesk lets you view, like, comment, and download Instagram pictures/videos! (NO Uploads! / Image Posting! Instagram forbids that! AND you *need* an *existing* Instagram account). But you can do... Read more

Latest Forum Discussions

See All

Ubisoft Gives Everyone Two New Ways to E...
Ubisoft Gives Everyone Two New Ways to Earn In-Game Stuff for Far Cry 4 Posted by Jessica Fisher on November 21st, 2014 [ permalink ] | Read more »
Golfinity – Tips, Tricks, Strategies, an...
Dig this: Would you like to know what we thought of being an infinite golfer? Check out our Golfinity review! Golfinity offers unlimited ways to test your skills at golf. Here are a few ways to make sure your score doesn’t get too high and your... | Read more »
Dark Hearts, The Sequel to Haunting Meli...
Dark Hearts, The Sequel to Haunting Melissa, is Available Now Posted by Jessica Fisher on November 21st, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Meowza! Toyze Brings Talking Tom to Life...
Meowza! | Read more »
Square Enix Announces New Tactical RPG f...
Square Enix Announces New Tactical RPG for Mobile, Heavenstrike Rivals. Posted by Jessica Fisher on November 21st, 2014 [ permalink ] With their epic stories and gorgeous graphics, | Read more »
Quest for Revenge (Games)
Quest for Revenge 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: The great Kingdom of the west has fallen. The gods ignore the prayers of the desperate. A dark warlord has extinguished... | Read more »
Threadz is a New Writing Adventure for Y...
Threadz is a New Writing Adventure for You and Your Friends Posted by Jessica Fisher on November 21st, 2014 [ permalink ] In the tradition of round-robin storytelling, | Read more »
SteelSeries Stratus XL Hardware Review
Made by: SteelSeries Price: $59.99 Hardware/iOS Integration Rating: 4 out of 5 stars Usability Rating: 4.5 out of 5 stars Reuse Value Rating: 4.25 out of 5 stars Build Quality Rating: 4.5 out of 5 stars Overall Rating: 4.31 out of 5 stars | Read more »
ACDSee (Photography)
ACDSee 1.0.0 Device: iOS iPhone Category: Photography Price: $1.99, Version: 1.0.0 (iTunes) Description: Capture, perfect, and share your photos with ACDSee. The ACDSee iPhone app combines an innovative camera, a powerful photo... | Read more »
ProTube for YouTube (Entertainment)
ProTube for YouTube 2.0.2 Device: iOS Universal Category: Entertainment Price: $1.99, Version: 2.0.2 (iTunes) Description: ProTube is the ultimate, fully featured YouTube app. With it's highly polished design, ProTube offers ad-free... | Read more »

Price Scanner via MacPrices.net

Save up to $400 with Apple refurbished 2014 1...
The Apple Store has restocked Apple Certified Refurbished 2014 15″ Retina MacBook Pros for up to $400 off the cost of new models. An Apple one-year warranty is included with each model, and shipping... Read more
New 13-inch 1.4GHz MacBook Air on sale for $8...
 Adorama has the 2014 13″ 1.4GHz/128GB MacBook Air on sale for $899.99 including free shipping plus NY & NJ tax only. Their price is $100 off MSRP. B&H Photo has the 13″ 1.4GHz/128GB MacBook... Read more
Apple Expected to Reverse Nine-Month Tablet S...
Apple and Samsung combined accounted for 62 percent of the nearly 36 million branded tablets shipped in 3Q 2014, according to early vendor shipment share estimates from market intelligence firm ABI... Read more
Stratos: 30 Percent of US Smartphone Owners t...
Stratos, Inc., creator of the Bluetooth Connected Card Platform, has announced results from its 2014 Holiday Mobile Payments Survey. The consumer survey found that nearly one out of three (30 percent... Read more
2014 1.4GHz Mac mini on sale for $449, save $...
 B&H Photo has lowered their price on the new 1.4GHz Mac mini to $449.99 including free shipping plus NY tax only. Their price is $50 off MSRP, and it’s the lowest price available for this new... Read more
Check Apple prices on any device with the iTr...
MacPrices is proud to offer readers a free iOS app (iPhones, iPads, & iPod touch) and Android app (Google Play and Amazon App Store) called iTracx, which allows you to glance at today’s lowest... Read more
64GB iPod touch on sale for $249, save $50
Best Buy has the 64GB iPod touch on sale for $249 on their online store for a limited time. Their price is $50 off MSRP. Choose free shipping or free local store pickup (if available). Sale price for... Read more
15″ 2.2GHz Retina MacBook Pro on sale for $17...
 B&H Photo has the 2014 15″ 2.2GHz Retina MacBook Pro on sale for $1799.99 for a limited time. Shipping is free, and B&H charges NY sales tax only. B&H will also include free copies of... Read more
New Logitech AnyAngle Case/Stand Brings Flexi...
Logitec has announced the newest addition to its suite of tablet products — the Logitech AnyAngle. A protective case with an any-angle stand for iPad Air 2 and all iPad mini models, AnyAngle is the... Read more
Notebook PC Shipments Rise Year-Over-Year as...
According to preliminary results from the upcoming DisplaySearch Quarterly Mobile PC Shipment and Forecast Report, the global notebook PC market grew 10 percent year-over-year in Q3’14 to 49.4... Read more

Jobs Board

*Apple* Solutions Consultant (ASC)- Retail S...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Project Manager, *Apple* Financial Services...
**Job Summary** Apple Financial Services (AFS) offers consumers, businesses and educational institutions ways to finance Apple purchases. We work with national and Read more
*Apple* Store Leader Program - College Gradu...
Job Description: Job Summary As an Apple Store Leader Program agent, you can continue your education as you major in the art of leadership at the Apple Store. You'll Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.