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A Brief History of UNIX

by Sam Coniglio
Contract Technical Writer
Email: spaceman@mindspring.com
September 07, 1999


In the beginning, there was AT&T.

Bell Labs’ Ken Thompson developed UNIX in 1969 so he could play games on a scavenged DEC PDP-7. With the help of Dennis Ritchie, the inventor of the “C” programing language, Ken rewrote UNIX entirely in “C” so that it could be used on different computers. In 1974, the OS was licensed to universities for educational purposes. Over the years, hundreds of people added and improved upon the system, and it spread into the commercial world. Dozens of different UNIX “flavors” appeared, each with unique qualities, yet still having enough similarities to the original AT&T version. All of the “flavors” were based on either AT&T’s System V or Berkeley System Distribution (BSD) UNIX, or a hybrid of both. During the late 1980’s there were several of commercial implementations of UNIX:

  • Apple Computer’s A/UX
  • AT&T’s System V Release 3
  • Digital Equipment Corporation’s Ultrix and OSF/1 (renamed to DEC UNIX)
  • Hewlett Packard’s HP-UX
  • IBM’s AIX
  • Lynx’s Real-Time UNIX
  • NeXT’s NeXTStep
  • Santa Cruz Operation’s SCO UNIX
  • Silicon Graphics’ IRIX
  • SUN Microsystems’ SUN OS and Solaris


... and dozens more.

The Open Standards Foundation is a UNIX industry organization designed to keep the various UNIX flavors working together. They created operating systems guidelines called POSIX to encourage inter-operability of applications from one flavor of UNIX to another. Portability of applications to different gave UNIX a distinct advantage over its mainframe competition.

Then came the GUIs. Apple’s Macintosh operating system and Microsoft’s Windows operating environment simplified computing tasks, and made computers more appealing to a larger number of users. UNIX wizards enjoyed the power of the command line interface, but acknowledged the difficult learning curve for new users. The Athena Project at MIT developed the X Windows Graphical User Interface for UNIX computers. Also known as the X11 environment, corporations developed their own “flavors” of the UNIX GUIs based on X11. Eventually, a GUI standard called Motif was generally accepted by the corporations and academia.

During the late 1990’s Microsoft’s Windows NT operating system started encroaching into traditional UNIX businesses such as banking and high-end graphics. Although not as reliable as UNIX, NT became popular because of the lower learning curve and its similarities to Windows 95 and 98. Many traditional UNIX companies, such as DEC and Silicon Graphics, abandoned their OS for NT. Others, such as SUN, focused their efforts on niche markets, such as the Internet.

Linus Torvalds had a dream. He wanted to create the coolest operating system in the world that was free for anyone to use and modify. Based on an obscure UNIX flavor called MINIX, Linus took the source code and created his own flavor, called Linux. Using the power of the Internet, he distributed copies of his OS all over the world, and fellow programmers improved upon his work. In 1999, with a dozen versions of the OS and many GUIs to choose from, Linux is causing a UNIX revival. Knowing that people are used to the Windows tools, Linux developers are making applications that combine the best of Windows with the best of UNIX.



A Brief OS Comparison

It would be impossible to create a complete comparison of commands without creating a book, so here are a few examples. I compare some common UNIX commands with MS-DOS, MS Windows and Apple Macintosh. All of the OSs have similar functions, but implement them slightly differently.



UNIX and MS-DOS

At first glance, the UNIX command line looks a lot like MS-DOS command line. In fact, some of the commands are the same. Then subtle differences appear. The DOS prompt looks like C:\ while the UNIX prompt looks like “$” or “#” The slashes are different: DOS uses the backslash “\” while UNIX uses the forward slash “/ ”. Finally, for each UNIX command, there are a ton of switches to customize the output of the command.

To ...UNIXMS-DOS
display list of filesls OR ls -ldir/w dir
display contents of filecattype
display file with pausesmoretype <filename> | more
copy filecpcopy
find string in filegrep OR fgrepfind
compare filesdiffcomp
rename filemvrename OR ren
delete filermerase OR del
delete directoryrmdirrmdir OR rd
change file protectionchmodattrib
create directorymkdirmkdir OR md
change working directorycdchdir OR cd
get helpman OR aproposhelp
display date and timedatedate, time
display free disk spacedfchkdsk
print filelprprint
display print queuelpqprint
kill a crashed programkill



UNIX and Windows

With the advent of Microsoft Windows, many of the DOS command line functions became abstract. Document icons represent files and folder icons represent directories. But Windows is still glued to its command line past. Just click on the “Start” button, select the “Run” command, type cmd in the text field, click the OK button, and poof!! Good old DOS command line appears in a new window.

To ...UNIXMicrosoft Windows
display list of filesls OR ls -lDouble-click on My Computer, or activate Windows Explorer. In View menu choose “Details”
display contents of filecatDouble-click on an icon
display file with pausesmoreClick on the scroll arrows
copy filecpSelect Icon, choose Copy from Edit menu, or from right mouse menu
find string in filegrep OR fgrepNot in OS, but third party tools available
compare filesdiffNot in OS but third party products available
rename filemvClick on file’s name, or choose Rename from right mouse menu
delete filermSelec t icon and press Delete key
delete directoryrmdirSelect icon and press Delete key
change file protectionchmodSelect icon, choose Properties from right mouse menu, click on Read-only checkbox
create directorymkdirChoose New->Folder from the File menu
change working directorycdDouble-click on a folder icon
get helpman OR aproposSelect Help menu
display date and timedateDate and time displayed on task bar
display free disk spacedfClick on disk icon, and capacity pie chart appears (Win98 Explorer mode) or space available displays in info bar (Windows Explorer)
print filelprCtrl-p (most programs)
display print queuelpqDouble-click on printer icon on task bar
kill a crashed programkillCtrl-Alt-Del, select application from list, click End Task button



UNIX and Macintosh

Apple’s Macintosh operating system was designed from the ground up as graphical OS. There are no command line shells like MS Windows. This make life easy for people new to computers, but it can be frustrating for DOS and UNIX experts. With the upcoming MacOS X, a Macintosh/UNIX hybrid, Apple may satisfy both new computer users and command line wizards.

To ...UNIXMacintosh
display list of filesls OR ls -lDouble-click on a folder or disk icon. In View menu choose “as List”
display contents of filecatDouble-click on an icon
display file with pausesmoreClick on the scroll arrows
copy filecpSelect Icon and press command-D
find string in filegrep OR fgrepCommand-F activates “Sherlock” tool, select “Find by Content” tab
compare filesdiffNot in OS but third party products available
rename filemvClick on file’s name
delete filermClick and drag icon to trash, or command-delete
delete directoryrmdirClick and drag icon to trash, or command-delete
change file protectionchmodGet Info on a file, click on lock button
create directorymkdirCommand-N
change working directorycdDouble-click on a folder icon
get helpman OR aproposSelect Help menu, or command-?
display date and timedateDate and time displayed on menu bar
display free disk spacedfFree space listed on top of each window
print filelprCommand-P
display print queuelpqDouble-click on printer icon on desktop
kill a crashed programkillCommand-Option-Esc



Web Sites for Reference

Here are some useful UNIX-related web sites. The Web has thousands more.

 

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