15-01-2013, 12:01 PM
System And Network Adminstration Insy 461
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Introduction to Linux
What is Linux?
• Operating System
What is Operating System?
• Wikipedia: “the system software responsible for the direct control
and management of hardware and basic system operations”.
Function of Operating system
– Memory management
– Process management
– Network management
– File management
– I/O management
What is kernel?
• A set of functions that make up the heart of
an OS
• It is used to provide an application interface
between programs and physical devices.
• Services provided by the kernel:
– Controls execution of processes.
– Scheduling processes fairly for execution on the
CPU.
– Allocating memory for an executing process.
What is Linux?
• A fully-networked 32/64-Bit Unix-like Operating
System
– Unix Tools Like sed, awk, and grep (explained later)
– Compilers and tools Like C, C++, Fortran, Smalltalk, Ada,
JDK, Python,
– Network Tools Like telnet, ftp, ping, traceroute
• Multi-user, Multitasking, Multiprocessor
• Has the X Windows GUI
• Coexists with other Operating Systems
• Runs on multiple platforms
• Includes the Source Code
History of Unix
• MULTICS PROJECT
– It was started in 1965 on Main frame GE 645 by the joint
effort of
– AT & T Bell Labs
• Multics was written in Assembly Language
• In 1969 Multics project was dropped.
• In 1969, Ken Thompson & Dennis Ritchie at Bell
Labs - AT&T redesigned the Multics and introduced
New OS
• UNICS (Uniplexed Information & computing system)
– It is written in 80 percent of C language and 20 percent
assembly language.
– Later on totally rewritten in C language and named as
UNIX (1973 )
Why Linux?
• Today Linux has joined the desktop market.
• On the server side, Linux is well-known as a
stable and reliable platform.
• Linux provides many applications like:
– Databases (MySQL,Postgresql),
– Network services(Web Servers,DNS, Proxy,
firewall etc)
– Software development tools(C, Java,
Python,Perl etc.)
– Office automation tools
– And many more…
Linux VS Windows NT
• Linux needs 2MB RAM to try out, while NT needs 12
MB
• Linux needs at least 15 MB disk space, while NT needs
70 MB at least.
• Both system support multitasking
• Both system support multiprocessing.
• Both system support dynamic cache.
• Linux has full multi user support. Local users, modem
users, and network users can all simultaneously run
text and graphics programs. This is a powerful feature
for business environments that is unmatched by NT.
anage users
• Under Linux, every file and program must be
owned by a user.
• Each user has a unique identifier called a user ID
(UID).
• Each user must also belong to at least one group (
collection of users established by the system
administrator).
• Users may belong to multiple groups.
• Like users, groups also have unique identifiers,
called group IDs (GIDs).
• A running pro-gram inherits the rights and
permissions of the user who invokes it