The Unix system is a multi-user, multi tasking operating system which means that it allows a single or multiprocessor computer to simultaneously execute several programs by one or several users. It has one or several command interpreters (shell) as well as a great number of commands and many utilities (assembler, compilers for many languages, text processing, email, etc.). Furthermore, it is highly portable, which means that it is possible to implement a Unix system on almost all hardware platforms.
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The history of UNIX systems
The first "Unix" system was developed by Ken Thompson in the Bell AT&T laboratories at Murray Hill in New Jersey in the United States from 1965. Ken Thompson's aim was to develop a simple interactive operating system, called "Multics" (Multiplexed Information and Computing System) in order to run a game which he had created (space travel, a simulation of the solar system).
A consortium made up of MIT (Massachesetts Institute of Technology), General Electric Co. and Bell Lab was then formed around Multics.
In April 1969 the AT&T laboratories decided to use the GECOS (General Electric Comprehensive Operating System ) instead of Multics. However, Ken Thompson and Dennis Ritchie who joined the team needed to make the space travel game work on a smaller machine (a DEC PDP-7, Programmed Data Processor which only had 4K of memory to make user programs run), this is why they recreated the system in order to create a limited version of Multics called UNICS (UNiplexed Information and Computing Service), quickly shortened to Unix.
The date of 1st January 1970 is considered as the birth date of the UNIX system, which explains why all system clocks for Unix operating systems start from this date.
Alongside these activities, D.Ritchie played a large part in the definition of the C language (since he is considered as one of its creators with B.W.Kernighan), so the whole system was entirely rewritten in C in 1973 and called Unix Time-Sharing System (TSS).
Use the following commands to help you manage your UNIX account.
The UNIX (Ultrix) operating system is case se
nsitive. All commands must be typed in lower-case
letters unless noted otherwise.
-- Lists the names of files in a particular
UNIX directory. If you type the ls command
with no parameters or qualifiers, the co
displays the files listed in your current working directory. When you give the ls command, you can add one or more modifiers to
Result: Lists the names of files in your de
fault directory, in alphabetical order.
Result: Gives a "long listing" of the files in
your directory. In addition to the f
ile name, the long listing shows protection
file owner, number of characters
in file, and the date and time of the last change to the file.
Result: Causes all your files to be listed, including thos
e files that begin with a period (i.e., hidden files).
For more information, type
at the UNIX system prompt.
-- Enables examination of a continuous text one screenful at
a time on a terminal. It normally
pauses after each screenful,
printing -- More -- at the bottom of the screen. Press
to display one more line. Press the
another screenful. Press the letter Q to stop displaying the file.
Result: Displays the contents of “newf
ile” one screen ("page") at a time.
For more information about this command, type
at the UNIX system prompt.
-- Displays the contents of a file on your terminal.
Result: Displays the contents of th
e file “newfile” on your terminal.
Result: Displays the contents of two files -- “newfile” and
“oldfile” -- on your terminal as one continuous display.
