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1.1
The Unix System
Unix is a Multi-user and Multi-tasking operating
system History
MULTICS (MULTIplexed Information and ComputingService) (1965)
Ken Thompson (Bell Laboratories -1969)Space Wars, PDP-7, written in ASSEMBLER
UNICS (UNiplexed Information and Computing Service)
Ken Thompson, Dennis Ritchie (1970-1974)
UNIX, PDP-11
Ritchie develops C language (starting from B language)
The third version of UNIX is written in C
A paper on UNIX is published in 1974 (ACM TuringAward 1984)
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1.2
The Unix System
History,Bell Labs and AT&T UNIX PDP-11 is the computer of many departments of computer
science and so UNIX becomes the OS of the Universities
Bell Labs and AT&T UNIX development groups develop severalversion of UNIX:
first edition (1969), ,seventh edition (1978,on PDP-11/70)
a version for Interdata 8/2 and VAX UNIX for a network of computers
System III (1982 - first commercial version)
System V based on System III(1983)
System V release 2, 3, 4 (1984 - 1989)
SVR4 (System V release 4; 1989 AT&T and Sun Microsystems)
1993: AT&T becomes a phone company and sells UNIX toNovell
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1.3
The Unix System History University of California at Berkeley
The most influential of the non-Bell Labs and non-AT&T
UNIX development groups:.Thompson and some students develop 1BSD (Berkeley
Software Distributions) starting from sixth edition (the first oneout of Bell Labs) (1978).
3BSD - 4BSD UNIX resulted from DARPA funding to develop
a standard UNIX system for government use.This series contains 4.1BSD, 4.2BSD, 4.3BSD and 4.4BSD
(1980-93) and has some important new tools: virtual memory,paging, multiuser, network connection by means of TCP/IP.
4.2BSD contains the text editorvi, the shell csh, Pascal and
Lisp compilers,
Sun Microsystem, DEC and some other companiesdecides to develop their UNIX version starting from BSDversions instead of System V.
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1.4
History of
UNIX Versions
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1.5
The Standardization Projects
History
Several standardization projects seek to consolidate thevariant flavors of UNIX leading to one programming
interface to UNIX. The most important are:
POSIX (Portable Operating System): merge of System V
and BSD (1984)
IBM, DEC, Hewlett-Packard create OSF (Open Software
Foundation) and their UNIX system is OSF/1 (1988)
X/OPEN defines the Single UNIX specification (1993) and
the systems satisfying this specification have the trademark
UNIX 95Open group (merge of Open Software Foundation and
X/OPEN; http://www.opengroup.com 1996)
Definition of the second version of the Single UNIX
specification (1997) with the trademark UNIX 98
http://www.opengroup.com/http://www.opengroup.com/http://www.opengroup.com/http://www.opengroup.com/http://www.opengroup.com/http://www.opengroup.com/http://www.opengroup.com/http://www.opengroup.com/7/28/2019 Bash Scripts Basic
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1.6
A variant of the UNIX System
Although there are many version of UNIX, themost important companies provide versionbased on UNIX System V Release 4 (SVR4) andthe last the Single UNIX specification ex. Solaris 2.x is the most widely used and most
successful commercial UNIX implementation.
These systems are very big and verycomplicated (the contrary of the Thompsonsbasic idea) and in same case expensive.
So, Tanenbaum develops MINIX (1987) a smallfree UNIX system (11800 rows of C code and800 rows of Assembler code) satisfying POSIX.MINIX is a free educational system based on micro-
kernel model (www.cs.vu.nl/~ast/minix.html)
http://www.cs.vu.nl/~ast/minix.htmlhttp://www.cs.vu.nl/~ast/minix.htmlhttp://www.cs.vu.nl/~ast/minix.htmlhttp://www.cs.vu.nl/~ast/minix.htmlhttp://www.cs.vu.nl/~ast/minix.htmlhttp://www.cs.vu.nl/~ast/minix.htmlhttp://www.cs.vu.nl/~ast/minix.htmlhttp://www.cs.vu.nl/~ast/minix.htmlhttp://www.cs.vu.nl/~ast/minix.htmlhttp://www.cs.vu.nl/~ast/minix.html7/28/2019 Bash Scripts Basic
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1.7
Common System Components of an OS
Process Management
Main Memory Management
File Management
Secondary Memory Management
I/O System Management
Networking
Protection System
Command-Interpreter System (Shell)
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1.8
System Structure
System structure: defines the connectionsand manages the System Components
Some system structuresa. Monolithic
b. Client-Server model (micro-kernel)
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1.9
Monolithic Operating System Structure
A monolithic system has not a well defined structure. Itincludes virtually all of the operating-system functionalityin one large block of code that runs as a single processwith a single address space. All the functionalcomponents of the kernel have access to all of its internaldata structures and routines.
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1.10
The Client-Server Model
Moves as much from the kernel into user
space. In this way it remains only a micro-kernel.
Communication takes place between user
modules using message passing.
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1.11
The Client-Server Model
Advantages
easier to extend a micro-kernel
easier to port the operating system to new architectures
more reliable (less code is running in kernel mode)
more secure
Disadvantages
Deterioration of the performances
MINIX has the I/O drivers into the kernel (this is for
technical reasons connected to 8088 architecture), while
the Main Memory Management, and the File
Management are two different user processes.
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1.12
The Linux System
There is not a free BSD system at the end of the
eighties, and so many members of MINIXnewsgroup ask to Tanenbaum to introduce many
modifications for improving the performances of
MINIX. Some of these modifications could
change the original educational project ofTanenbaum, and so often he said NO to these
requests.
So, Linus Torvalds using a pc 386 with MINIXdevelops a small but self-contained kernel in
1991 (Linux 0.01), with the major design goal of
UNIX compatibility (i.e., satisfying POSIX).
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1.13
Linux 0.01
The first version of Linux (Linux 0.01) has some of
features of MINIX (ex. File system), but the maindifferences between Linux and MINIX are: The Linux kernel uses a monolithic model, and it has
many more functions than the micro-kernel of MINIX.
From a theoretical point of view MINIX is better thanLinux, but from a practical point of view theperformances of Linux are better than that one ofMINIX.
However, for a description of the point of view of
Torvalds on the advantages-disadvantages of Linux-MINIX see the flame war between Torvalds andTanenbaum in:
Rivoluzionario per caso: come ho creato Linux (solo perdivertirmi), Linus Torvalds, Garzanti
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1.14
The Linux Kernel
Linux 0.01 (May 1991) had no networking, ran only on80386-compatible Intel processors and on PC hardware,
had extremely limited device-drive support, and supportedonly the Minix file system.
Linux 1.0 (March 1994) included these new features: Support forUNIXs standard TCP/IP networking protocols
BSD-compatible socket interface for networking programming
Device-driver support for running IP over an Ethernet
Enhanced file system
Support for a range of SCSI controllers for high-performance diskaccess
Extra hardware support
This version is sufficient compatible with UNIX and manypeople are interested in developing Linux under Torvaldsupervision.
Linux 1.2 (March 1995) was the final PC-only Linux kernel.
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1.15
Linux 2.0 Released in June 1996, 2.0 added two major new
capabilities:
Support for multiple architectures Support for multiprocessor architectures
Other new features included: Improved memory-management code
Improved TCP/IP performance
Support for internal kernel threads, for handling dependenciesbetween loadable modules, and for automatic loading of modules ondemand.
Standardized configuration interface
Available for Motorola 68000-series processors, Sun Sparc
systems, and for PC and PowerMac systems. Linux 2.2 January 1999 improves some aspects of Linux 2.0
The last release is Linux 2.4.20 (production) Linux 2.5.64(development)
http://www.linuxhq.com/kernel/v2.4/20/index.htmlhttp://www.linuxhq.com/kernel/v2.5/64/index.htmlhttp://www.linuxhq.com/kernel/v2.5/64/index.htmlhttp://www.linuxhq.com/kernel/v2.5/64/index.htmlhttp://www.linuxhq.com/kernel/v2.5/64/index.htmlhttp://www.linuxhq.com/kernel/v2.5/64/index.htmlhttp://www.linuxhq.com/kernel/v2.5/64/index.htmlhttp://www.linuxhq.com/kernel/v2.5/64/index.htmlhttp://www.linuxhq.com/kernel/v2.5/64/index.htmlhttp://www.linuxhq.com/kernel/v2.4/20/index.htmlhttp://www.linuxhq.com/kernel/v2.4/20/index.htmlhttp://www.linuxhq.com/kernel/v2.4/20/index.htmlhttp://www.linuxhq.com/kernel/v2.4/20/index.htmlhttp://www.linuxhq.com/kernel/v2.4/20/index.htmlhttp://www.linuxhq.com/kernel/v2.4/20/index.htmlhttp://www.linuxhq.com/kernel/v2.4/20/index.html7/28/2019 Bash Scripts Basic
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1.16
The Moral of the Story
Linux is a modern, free operating system based on UNIXstandards.
First developed as a small but self-contained kernel in1991 by Linus Torvalds, with the major design goal ofUNIX compatibility.
Its history has been one of collaboration by many users
from all around the world, corresponding almostexclusively over the Internet (software open source).
It has been designed to run efficiently and reliably oncommon PC hardware, but also runs on a variety of otherplatforms.
The core Linux operating system kernel is entirelyoriginal, but it can run much existing free UNIX software,resulting in an entire UNIX-compatible operating systemfree from proprietary code.
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1.17
The Linux System
Linux uses many tools developed as part ofBerkeleys BSD
operating system, System V, MITs X Window System, andthe Free Software Foundation's GNU project.
The main system libraries were started by the GNU (GNUs
Not Unix) project (ex. gcc (GNU C compiler)), with
improvements provided by the Linux community. Linux networking-administration tools were derived from 4.3
BSD code; recent BSD derivatives such as FreeBSD have
borrowed code from Linux in return.
The Linux system is maintained by a network of developerscollaborating on Internet (see /usr/src/linux/CREDITS), with
a small number of public ftp sites acting as de facto
standard repositories.
http://localhost/var/www/apps/conversion/tmp/scratch_4/gnu/Panoramica%20del%20Progetto%20GNU%20-%20Free%20Software%20Foundation%20(FSF).htmhttp://localhost/var/www/apps/conversion/tmp/scratch_4/gnu/Panoramica%20del%20Progetto%20GNU%20-%20Free%20Software%20Foundation%20(FSF).htmhttp://localhost/var/www/apps/conversion/tmp/scratch_4/gnu/Panoramica%20del%20Progetto%20GNU%20-%20Free%20Software%20Foundation%20(FSF).htmhttp://localhost/var/www/apps/conversion/tmp/scratch_4/gnu/Panoramica%20del%20Progetto%20GNU%20-%20Free%20Software%20Foundation%20(FSF).htmhttp://localhost/var/www/apps/conversion/tmp/scratch_4/gnu/Panoramica%20del%20Progetto%20GNU%20-%20Free%20Software%20Foundation%20(FSF).htmhttp://localhost/var/www/apps/conversion/tmp/scratch_4/gnu/Panoramica%20del%20Progetto%20GNU%20-%20Free%20Software%20Foundation%20(FSF).htmhttp://localhost/var/www/apps/conversion/tmp/scratch_4/gnu/Panoramica%20del%20Progetto%20GNU%20-%20Free%20Software%20Foundation%20(FSF).htmhttp://localhost/var/www/apps/conversion/tmp/scratch_4/gnu/Panoramica%20del%20Progetto%20GNU%20-%20Free%20Software%20Foundation%20(FSF).htmhttp://localhost/var/www/apps/conversion/tmp/scratch_4/gnu/Panoramica%20del%20Progetto%20GNU%20-%20Free%20Software%20Foundation%20(FSF).htmhttp://localhost/var/www/apps/conversion/tmp/scratch_4/gnu/Panoramica%20del%20Progetto%20GNU%20-%20Free%20Software%20Foundation%20(FSF).htm7/28/2019 Bash Scripts Basic
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1.18
Linux Distributions
Standard, precompiled sets of packages, or distributions,
include the basic Linux system, system installation andmanagement utilities, and ready-to-install packages of
common UNIX tools.
The first distributions managed these packages by simply
providing a means of unpacking all the files into theappropriate places; modern distributions include advanced
package management.
Red Hat, Debian, SuSE, Mandrake are popular
distributions from commercial and noncommercial sources,
respectively (see www.linux.org).
The RPM Package file format permits compatibility among
the various Linux distributions (see www.linuxbase.org).
http://www.linux.org/http://www.linuxbase.org/http://www.linuxbase.org/http://www.linuxbase.org/http://www.linuxbase.org/http://www.linuxbase.org/http://www.linuxbase.org/http://www.linux.org/http://www.linux.org/http://www.linux.org/http://www.linux.org/http://www.linux.org/7/28/2019 Bash Scripts Basic
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1.19
Which distribution to use ?
RedHat (www.redhat.com)
Big, professional, very widely used
Debian (www.debian.org/)
Open development model, excellent packaging
system
Mandrake (www.mandrakesoft.com)
Aims to be very easy to install and use
SuSE (www.suse.com/)
Compromise between Red Hat and Mandrake
Slackware (www.slackware.com/)
Most traditional; little extra help
http://www.redhat.com/http://www.debian.org/http://www.mandrakesoft.com/http://www.suse.com/http://www.slackware.com/http://www.slackware.com/http://www.slackware.com/http://www.slackware.com/http://www.slackware.com/http://www.slackware.com/http://www.suse.com/http://www.suse.com/http://www.suse.com/http://www.suse.com/http://www.suse.com/http://www.mandrakesoft.com/http://www.mandrakesoft.com/http://www.mandrakesoft.com/http://www.mandrakesoft.com/http://www.mandrakesoft.com/http://www.debian.org/http://www.debian.org/http://www.debian.org/http://www.debian.org/http://www.debian.org/http://www.redhat.com/http://www.redhat.com/http://www.redhat.com/http://www.redhat.com/http://www.redhat.com/7/28/2019 Bash Scripts Basic
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1.20
Mandrake Distribution
Mandrake provides a simple and friendly
distribution. Maybe, it is the best distribution for thedesktop (www.mandrakesoft.com).
The last release of Mandrake distribution isMandrake 9.0 Dolphin and it is contained in three
CDs. It contains the Linux kernel 2.4.19. The minimum installation requires only the first
CD and takes only 60MB. The other two CDcontain many packages.
There are two different GUI (Graphical UserInterface): KDE (release 3.0.3) and GNOME (2.0.1)
http://www.mandrakesoft.com/http://www.mandrakesoft.com/http://www.mandrakesoft.com/http://www.mandrakesoft.com/http://www.mandrakesoft.com/http://www.mandrakesoft.com/7/28/2019 Bash Scripts Basic
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1.21
Mandrake Installation
The installation of Mandrake 9.0 Dolphin is very easy. You can select Italian language
The first time you should choose the installation forprincipiante
The more difficult step is the partition of the hard disk. Apartition correspond to a logic disk. If you want to installsome operating systems on your hard disk, you have to define
a partition for each OS. A disk has at most 4 primarypartitions. You can make these partitions by means of thecommand fdisk.The Mandrake installation provides asimple graphical tool for making the Linux partitions.
We wish to point out that from DOS/Windows you cannot see
the other partitions. On the contrary, Linux see DOS/Windowspartition (/mnt/windows).
However, all the steps of the installation will beillustrated during the lecture.
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1.22
The Moral of the Installation
Varies from distribution to distribution
Most modern distributions make it easy: Buy CD / download and burn CD image
Boot
Follow instructions
Need to think about partitioning.
Install a boot loader (probably LILO (LInux
LOader), maybe something else). This needs tobe configured to boot whatever other operatingsystems you have installed.
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1.23
Users Linux is an intrinsically multi-user system
Every user on the system has its own username
and password The root user has ultimate power to run the
system. You should not log in as rootunlessyou really need to.
During installation, you should have beenprompted for a root password and also ausername and password for an ordinary useraccount.
The commandpasswd allows to change thepassword.
Careful: you have to perform the programshutdown h now before to switch off the PC
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1.24
Linux Licensing
The Linux kernel is distributed under the GNU
General Public License (GPL), the terms of whichare set out by the Free Software Foundation. See /usr/src/linux/COPYING
The main consequence of GPL is that anyoneusing Linux, or creating their own derivative ofLinux, may not make the derived productproprietary; software released under the GPL may
not be redistributed as a binary-only product.
For a deeper examination of this subject seewww.gnu.org/home.it.html
http://www.gnu.org/home.it.htmlhttp://www.gnu.org/home.it.htmlhttp://www.gnu.org/home.it.htmlhttp://www.gnu.org/home.it.htmlhttp://www.gnu.org/home.it.htmlhttp://www.gnu.org/home.it.htmlhttp://www.gnu.org/home.it.htmlhttp://www.gnu.org/home.it.htmlhttp://www.gnu.org/home.it.htmlhttp://www.gnu.org/home.it.html