26-04-2012, 11:36 AM
Linux
Intro_linux.pdf (Size: 537.7 KB / Downloads: 56)
What is Linux
A fully-networked 32/64-Bit Unix-like Operating System
Unix Tools Like sed, awk, and grep (explained later)
Compilers Like C, C++, Fortran, Smalltalk, Ada
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
Software
When programmers on the Internet can
read, redistribute, and modify the source
for a piece of software, it evolves
People improve it, people adapt it, people
fix bugs. And this can happen at a speed
that, compared to conventional software
development, seems astonishing
How do you get it?
Download it from the Internet
From a “Distribution” (e.g. RedHat)
Linux kernel
X Windows system and GUI
Web, e-mail, FTP servers
Installation & configuration support
3rd party apps
Hardware support
Why is it significant?
Growing popularity
Powerful
Runs on multiple hardware platforms
Users like its speed and stability
No requirement for latest hardware
It’s “free”
Licensed under GPL
Vendors are distributors who package Linux
Virtual File System
Logical file systems promote compatibility
with other operating system standards
permitting developers to implement file
systems with different policies
VFS abstracts details of physical device
and logical file system allowing processes
to access files using a common interface,
without knowing what physical or logical
system the file resides on
Processes - UID & GID
Effective UID
The effective UID is used to determine owner
access privileges of a process.
Normally the same as the real UID. It is possible for
a program to have a special flag set that, when this
program is executed, changes the effective UID of
the process to the UID of the owner of the program.
A program with this special flag set is said to be a
set-user-ID program (SUID). This feature provides
additional permissions to users while the SUID
Linux’s place in the market
Challenges for growth
Products/Technologies/Offerings
Support services
ISV applications
Service providers
Trends
Movement to mainstream
Standards
Ease of use
program is being executed.