Peter Roll
Sun City TX Computer Club
Advanced Technology SIG
March 18, 2003

Summary: topics to be covered

• Developed by computer scientists at Bell Labs in 1969, for minicomputers (new) for basic science and engineering research; handled numerical calculations, text manipulation, and all sorts of symbol-processing.
• UC Berkeley Computer Science Department extended and developed a new dialect of Unix during the 1970's, which came to be called the Berkeley Software Distribution (BSD Unix).
• Government agencies, the computer industry, and foreign governments wanted a standard version of Unix that would always produce identical results for calculations.
• Computer scientists representing the profession and these groups defined the Posix standard for Unix; the Berkeley Computer Science Department made its BSD Unix the first implementation of Posix.
• In the meantime, many computer manufacturers devised their own proprietary operating systems and versions of Unix, and the Posix standard has largely been forgotten.
  

• When Steve Jobs was fired as President of Apple Computer in 1986, he founded the Next Computer company.
• Next developed a computer system using Motorola processors and the NextStep operating system based on BSD Unix with an advanced graphical user interface and application development system.
• Later, Next ported the NextStep OS to run on standard Intel-based PC computers, thus enlarging their potential market.
  

• By the time Apple purchased Next in 1997, Apple had begun allowing 3rd parties to build and sell Mac-OS-based computers and had started a project, code-named  Copland, to develop a new operating system eliminating some of the limitations built into the original Mac OS.
• Shortly after Apple purchased Next, Steve Jobs was named Interim President; his two major actions were to discontinue allowing Mac clones to be sold; and to initiate a review of the Copland project.  
• Jobs and the senior technical staff brought over from Next concluded that the Copland project would fail.
• They developed an alternative OS strategy based on the NextStep approach, using BSD Unix as the foundation of the new OS and building an entirely new graphical user interface on top of it.
• The most difficult problem in developing the new OS (Copland or NextStep-based) was to allow old Mac proglrams to continue to function under the new OS, knowing this would be required while users adapted and accepted the new OS and developers rewrote their application programs.
• The solution to this problem was to allow old Mac OS to run under the new OS in so-called "classic mode," thus preserving the look-and-feel of the old OS and the functionality of the old programs.

Why Unix?  What does it do that other PC OS's didn't do (Windows and Mac)?

---

2. How it's put together (a little architecture...)




Some important characteristics of Unix operating systems:

• settings controlled by small text-based files
• settings files created and changed with simple text editor
• highly-coded text,
• so its easy to read and change (for anybody who knows the code!)
• easy to learn (for those who learn codes easily!)
• and it led to a weird jargon, including the word Geek
• and ... the most important characteristics of 
• preemptive multitasking, 
• protected memory, 
• multiprocessor support 
• scalability

---

3. How it works (scratching the surface just a little...)

a. Important notes:  

• Unix is case-sensitive
• not consistently, but when you least expect it and when it is most annoying or damaging
• convention: always use lower-case characters

Last login: Sun Mar 16 15:03:06 on ttyp1 Welcome to Darwin! [Peter-Rolls-Computer:~] proll%

Date, time, device Welcome [Name of computer: active directory] username

Unix directory	a folder in Mac or Windows lingo
Active directory	the one that all the action will take place in at any given time
root directory	at the root or top level of the hard disk
root directory	/
active user account home directory	~
pathnames in the file
full pathname, e.g.	/Users/proll/Documents
pathname relative to active directory	/Documents
pathname relative to active user home directory	~/Documents
down one level in file system hierarchy	/dirname
up one level in the file system hierarchy (parent directory)	../
change active directory command	cd pathname (note the space as a delimiter!)

d. The Unix File system

The file system under Mac OS X (column view, similar to Windows Explorer -- shows  relative position of files and folders):





The actual file structure under Unix contains much more at the root level than is shown in the OSX finder!

[Peter-Rolls-Computer:~] proll% ls 100NIKON            Documents           Music               Send Registration Applications        Library             Pictures            Sites Desktop             Movies              Public [Peter-Rolls-Computer:~] proll% [Peter-Rolls-Computer:~] proll% cd / [Peter-Rolls-Computer:/] proll% ls ???Move&Rename            System                    etc AppleShare PDS            TheVolumeSettingsFolder   mach Applications              Trash                     mach.sym Desktop DB                Users                     mach_kernel Desktop DF                Volumes                   private Desktop Folder            automount                 sbin Library                   bin                       tmp Network                   cores                     usr Resources                 dev                       var [Peter-Rolls-Computer:/] proll% cd ~/documents [Peter-Rolls-Computer:~/documents] proll% cd ~/Documents [Peter-Rolls-Computer:~/Documents] proll% ls 8:27:02Apps.10.1.5.tiff                 Neighborhod#2.lst ACO                                     Neighborhood 2 DIR-2 Acrobat User Data                       Neighborhood 2 Dir AppleWorks User Data                    NewBookmarks.html BackupStuff                             NewBookmarks.html~ CD-RWSuppt.rtf                          Notes CompClub                                OSXInfo ComputerIcons.cwk                       OnlineOrders DVixDir.rtfd                            PIE.SCGT Email file (generic) #13726             Palm Eudora Folder                           Palmcopy020205 FAXReceive                              Personal:Family FloorPlan0211.gif                       Peter.fs GCN                                     Quintet GISDTechn.Cte                           RouterRef1.rtf GIVE                                    SchoolTaxDoc98.01 Gtwn+                                   Science IDs.rtf                                 ServicesReadMes IDsMaster.rtf                           ShowCase030218a.tiff ISPFAQ                                  SrUniv InstallFiles                            TB2MsgsRcvd InventoryTempl.sylk                     WebSites JohnsExcel                              WoodShop MAIN                                    eGtwn MacNews0201.rtf                         emailadrses030102.bk Microsoft User Data                     iNotePad User Data MiscRecFiles                            index3.html Move:Retirement.95 [Peter-Rolls-Computer:~/Documents] proll%

What's found in this Terminal window:

• initial active directory is active user's home directory (~)
• ls is the shell command to list the contents of the active directory
• cd / changes the active directory to root
• ls lists the contents of the root directory; note that there are several files listed that are missing from the OS X finder window -- these Unix directories are unneeded in OS X and they are hidden, visible only in the Terminal window
• cd ~/documents changes the active directory to the Documents directory in the active user's home directory
• note that the case of the first letter of the word directory doesn't make any difference!
• ls lists the files and directories in the active user's Documents director
  

Some notes on the File system, Unix and OS X:

 /Users/proll/documents/Compclub is the full path to my Computer Club folder; and that

~/Documents/Compclub is exactly the same path.

All info for a given user (settings, documents, etc.) is stored in the User Account Home directory (or folder) (similar to the Documents and Settings folder in Windows XP).
In the directory /Users/proll/ (same as ~/)

• the Documents directory-folder contains all user documents and other data (but you have to keep it this way!)
• ~/ Library directory-folder contains preferences or settings applicable  only to the active user account
• the /Library directory-folder contains preferences or settings applicable to all user accounts
  

Applications available for use by all user accounts are stored  in the root /Applications  directory-folder

Appllications available for use only by a given user are stored within the user's home directory-folder, ~/Applications

---

e. A few of the Unix Services:

(1) The Unix Shell: the tcsh shell is default for OS X

• but many other shells are available
• all shells are pretty similar -- they work the same way but have minor differences
• you can install other shells on OS X if you wish

(2) Some shell commands (Unix utility programs):

• Note that the spaces are essential delimiters
• options are of the format -x, where x is a code letter for an option
  

• type the command man commandname
• this displays the Unix manual page for the specified command -- try it!
  

(3) Some commands or services we've already seen (above):

• ls
• cd
• man
• ls -la (list showing details (l) and hidden files (a))
  

Last login: Sun Mar 16 16:33:30 on ttyp1 Welcome to Darwin! [Peter-Rolls-Computer:~] proll% cd / [Peter-Rolls-Computer:/] proll% ls ???Move&Rename            System                    etc AppleShare PDS            TheVolumeSettingsFolder   mach Applications              Trash                     mach.sym Desktop DB                Users                     mach_kernel Desktop DF                Volumes                   private Desktop Folder            automount                 sbin Library                   bin                       tmp Network                   cores                     usr Resources                 dev                       var [Peter-Rolls-Computer:/] proll% ls -la total 11273 drwxr-xr-x   2 proll  unknown       68 Jan  2 17:01 ???Move&Rename drwxr-xr-x  34 proll  staff       1156 Mar 16 14:37 . drwxr-xr-x  34 proll  staff       1156 Mar 16 14:37 .. -rwxr-xr-x   1 proll  staff      12292 Mar 16 14:37 .DS_Store d-wx-wx-wx   3 root   unknown      102 Sep  2  2002 .Trashes -r--r--r--   1 root   wheel        156 Jul 14  2002 .hidden dr--r--r--   2 root   wheel        160 Mar 16 11:21 .vol -rwxr-xr-x   1 proll  unknown   323584 Feb 27 02:35 AppleShare PDS drwxrwxr-x  53 root   admin       1802 Feb 26 20:14 Applications -rw-r--r--   1 root   admin     119296 Mar 16 13:36 Desktop DB -rw-r--r--   1 root   admin     841458 Mar 15 10:21 Desktop DF drwxr-xr-x   2 proll  unknown       68 Dec 20 21:51 Desktop Folder drwxrwxr-x  32 root   admin       1088 Feb 27 20:42 Library drwxr-xr-x   6 root   wheel        204 Aug 31  2002 Network drwxr-xr-x   4 root   staff        136 Mar 14 14:03 Resources drwxr-xr-x   4 root   wheel        136 Dec 15 03:07 System drwxr-xr-x   3 proll  unknown      102 Dec 20 21:51 TheVolumeSettingsFolder drwxr-xr-x   2 proll  unknown       68 Dec 20 21:51 Trash drwxrwxr-t   5 root   wheel        170 Aug 31  2002 Users drwxrwxrwt   5 root   wheel        170 Mar 16 11:21 Volumes dr-xr-xr-x   1 root   wheel        512 Mar 16 17:08 automount drwxr-xr-x  35 root   wheel       1190 Jan 25 12:19 bin drwxrwxrwt   2 root   wheel         68 Jul 14  2002 cores dr-xr-xr-x   2 root   wheel        512 Mar 16 11:21 dev lrwxr-xr-x   1 proll  staff         11 Mar 16 14:37 etc -> private/etc lrwxr-xr-x   1 proll  staff          9 Mar 16 14:37 mach -> /mach.sym -r--r--r--   1 root   staff     706480 Mar 16 11:21 mach.sym -rw-r--r--   1 root   wheel    3733424 Dec 14 05:11 mach_kernel drwxr-xr-x   6 root   wheel        204 Mar 16 11:21 private drwxr-xr-x  60 root   wheel       2040 Jan 25 12:19 sbin lrwxr-xr-x   1 proll  staff         11 Mar 16 14:37 tmp -> private/tmp drwxr-xr-x  10 proll  staff        340 Mar 14 14:03 usr lrwxr-xr-x   1 proll  staff         11 Mar 16 14:37 var -> private/var [Peter-Rolls-Computer:/] proll%

Some other useful commands:

Finding things on your hard disk:   locate pattern

• pattern is a string of characters that can be contained in a filename or directoryname; the command will find all files and directories with that string in its name;
• a database of file- and directorynames must be created before the locate command will work; this database is created by the command sudo /usr/libexec/locate.updatedb (note: this took about 5 minutes to complete on my computer);
• use the man locate command to find out more.

Printing and Piping:

enscript filename: converts a file to postscript for printing to a postscript printer (most laser printers)
atprint filename: prints a file to an AppleTalk printer; this command must be set up first with the commands

• atlookup to find all of the AppleTalk devices connected to the computer, followed by the superu command
• sudo at_cho_prn to select the device you want to use to print (lyou need the superuser or root password for this one).
  

If the AppleTalk printer is a postscript printer, then you must convert it to postscript before sending to the printer. The way to do this is to Unix's piping capability:  the pipe symbol | will pipe the output of one command into the input of the next; e.g., to print the manual page for the locate command,



Shell scripting, aka shell programming: the Unix alias:

[Peter-Rolls-Computer:~] proll% ls 100NIKON            Documents           Music               Send Registration Applications        Library             Pictures            Sites Desktop             Movies              Public [Peter-Rolls-Computer:~] proll% alias ls "/bin/ls -al" [Peter-Rolls-Computer:~] proll% ls total 56 drwxr-xr-x  17 proll  staff    578 Mar 16 14:37 . drwxrwxr-t   5 root   wheel    170 Aug 31  2002 .. -rw-r--r--   1 proll  staff      3 Dec 26 20:28 .CFUserTextEncoding -rwxr-xr-x   1 proll  staff  12292 Mar 16 14:37 .DS_Store drwx------  13 proll  staff    442 Mar 16 13:55 .Trash -rw-r--r--   1 proll  staff     31 Mar 13 12:09 .lpoptions drwxrwxrwx  10 proll  staff    340 Dec 21 07:25 100NIKON drwxr-xr-x   3 proll  staff    102 Sep  3  2002 Applications drwx------  23 proll  staff    782 Mar 16 14:37 Desktop drwx------  59 proll  staff   2006 Mar 15 22:05 Documents drwx------  39 proll  staff   1326 Feb  5 21:25 Library drwx------   4 proll  staff    136 Jan 18 18:54 Movies drwx------   7 proll  staff    238 Dec 18 13:03 Music drwx------  20 proll  staff    680 Mar 15 17:35 Pictures drwxr-xr-x   4 proll  staff    136 Aug 31  2002 Public lrwxr-xr-x   1 proll  staff     55 Mar 16 14:37 Send Registration -> /Users/proll/Library/Assistants/Send Registration.setup drwxr-xr-x   5 proll  staff    170 Aug 31  2002 Sites

---

4. What you can do with Unix if you're not a Geek:  normal applications software available

MS Office replacements:

• file compatibility with MS Word, Excel, PowerPoint (Open and Save as...)
• usually run in the X11window, so you need to install X11, too
• available for online download, often at no cost (but 1xx MB, so it takes a while), with X11 and everything else you need
• usually available on CD for $40-50, with X11 and everything else you need
• Examples:
• OpenOffice
• ThinkFree Office (written in Java, so it runs on every platform!)

Browsers:

• Netscape
• Mozilla
• Lynx (text-only, so it's fast, if nothing else)
• others....
  

Utilities:  thousands  of these

One example:  CarbonCopyCloner, by Mike Bombich

• a script invoking several pre-existing Unix programs to make a bootable copy of a hard disk and to back up all or parts of a hard disk to a variety of media (CD-R, a 2nd HD, etc.)
• downloadable giftware (pay the author what you want if it's been usefult to you)
• simple -- it just works
• no comparable simple program for Windows
  

The Good News: thousands of programs available at no cost, downloadable
The Bad News:  most of them are designed for other Geeks, rather than ordinary users,
but if there's something usable for just about every purpose if you are willing to look and tolerate a little geekiness.

---

5. The Geek's Business Model: the economics of Unix

The open-source movement -- an integral part of Unix:

From the Apple Darwin FAQ page:  

Q. What is open source?
Open source is a term for the historical development model used by the Internet community to facilitate distributed development of complex, high-quality software. The basic principle is to involve as many people as possible in writing and debugging code, by publishing the source code and encouraging the formation of a large community of developers who will submit modifications and enhancements. Community efforts such as BSD, Linux, Sendmail, Apache, and Perl embody the spirit and power of the open source model.

Q. Why is Apple opening up its source?
We believe the open source model is the most effective form of development for certain types of software. By pooling expertise with the open source development community, we expect to improve the quality, performance and feature set of our software.
Secondly, we realize many developers enjoy working with open source software, and we want to provide them the opportunity to use that kind of environment while delivering solutions for Apple customers.

The open-source movement is

• Diverse; based on several rather different kinds of open-source licensing:
• Open Software Foundation; the GNU license -- copyright; use requires that all derivative works go into public domain and be distributed;Free Software Foundation's General Public License (GPL),
• BSD license
• Apache license,
• Netscape and Mozilla Public Licenses
• Sun's Community Source License.
• Apple Public Source License

• Based on a fundamental difference between the economics of goods and services and the economics of information:
• goods and services: can be pounit value is reduced or eliminated by consumption
• information: value is increased by use and by the number of people using it; value is created by the consumers
• may require new business  models and a new form of economics that is not yet understood or even much studied
  

• Full of private and corporate ideological agendas, most of which have little to do with the realities of the world and how the future is likely to develop

6. A Few References: Unix under Mac OS X

Taylor and Peek, Learining Unix for Mac OS X; O'Reilly, Sebastopol, CA, 2002; 126 pgs.

O'Reilly is the definitive publisher of reference and textbooks on alll varieties of the Unix OS; see their website for many more useful references

Listing of  Unix & Open-Source programs that will run on OSX Macs: http://www.apple.com/downloads/macosx/unix_open_source/

Apple's Open-source Darwin home page; explains briefly the concept behind Apple's open-source approach and the architecture underneath OSX:  http://developer.apple.com/darwin/

The Fink Project " ...  bringing the full world of Unix Open Source software to Darwin and Mac OS X . We modify Unix software so that it compiles and runs on Mac OS X ("port" it) and make it available for download as a coherent distribution. Fink uses Debian tools like dpkg and apt-get to provide powerful binary package management. You can choose whether you want to download precompiled binary packages or build everything from source."  http://fink.sourceforge.net/

SourceForge.net:  " ... the world's largest Open Source software development website, with the largest repository of Open Source code and applications available on the Internet. SourceForge.net provides free services to Open Source developers."  http://sourceforge.net/

---