Transcript Chapter 10 – UNIX

Chapter 10 – UNIX
History
• In late 1960s, two employees of Bell Labs (Ken
Thompson & Dennis Ritchie) designed a new
operating system to overcome the constraints of
“batch processing” that was the norm at that time.
• This environment evolved into the UNIX
operating system
• For a small license fee, anyone could purchase the
source code for this operating system. It was
written in the C language and was very portable.
• Researchers at the Univ. of California at Berkley
added many features. This version became know
as Berkley Software Distribution (BSD)
History – Continued
• Bell Labs was broken into smaller organizational
units in the 1980s and they began to market and
sell UNIX to computer manufacturers.
• They finally sold their rights to UNIX
• Today, ownership is shared by the Santa Cruz
Operation (owns rights to UNIX source code) and
The Open Group (owns the UNIX trademark)
• Compaq pays sources code licensing fees to the
Santa Cruz Operation and trademark use fees to
the Open Group
Proprietary UNIX
• An implementation of UNIX for which the source
code is either unavailable or available only by
purchasing a licensed copy from the Santa Cruz
Operation
• Three most popular vendors of proprietary UNIX
– Sun Microsystems (Solaris)
– IBM (AIX)
– Hewlett-Packard (HP-UX)
Open Source UNIX
• UNIX-like systems that are not owned by any one
company
• Software is developed by individuals and made
available without license fees
• Versions of open source UNIX run on Intel
processors, PowerPC (Macintosh), SPARC (Sun),
and Alpha (Compaq)
• Linus was developed in 1991 by Linus Torvalds, a
Finnish scientist. After developing it, he posted it
on the Internet
Network Features of UNIX
• Includes TCP/IP protocol suite
• Provides routing, firewall, domain name service,
and automatics IP address assignment
• Supports Novell’s IPX/SPX and AppleTalk
• Supports many different network topologies and
physical media
• Can act as file servers to Windows, NetWare and
Macintosh clients
• Samba – is a complete Windows NT-style file and
print sharing facility
Network Features of UNIX –
Continued
• UNIX allows you to change configuration of
server without restarting server
• UNIX provides a time-sharing system: You must
log in and run applications to share its resources
• Provides a mature security model
• May be installed as a workstation or server,
depending upon the packages included during
installation
• Optional graphical interface
Linux Multiprocessing
• Supports symmetric multiprocessing
• Maximum of 16 processors per server
Linux Minimum Hardware
Requirements
• See p. 418 for Table 10-1
Linux Memory Model
• Allocates a memory area for each application
• Tries to share memory between programs
whenever it can
• Example: five instances of FTP running – most of
the program remains in memory shared by all five
instances. Only a small part of the FTP program
will receive its own memory space
• 32-bit addressing is used
• Virtual memory is supported
Linux Kernal
• Linux core of the OS is called the kernal
• The core is loaded into memory from disk and is
run when computer is turned on
• You can load and unload Linux kernal modules
which are similar to NetWare NLMs
Linux File and Directory Structure
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Hierarchical (tree) file system
This is similar to the NetWare NDS inverted tree
Today, most Oss use hierarchical file systems
/boot contains the Linux kernal
/home contains the users’ login directories
Linux File System
• Linux provides support for multiple types of file
systems
• The native file system type is called “ext2” which
stands for the second extended file system
Linux Internet Services
• Current implementations of UNIX include the
standard Internet services such as FTP, Telnet and
HTTP
• With Microsoft NT and Novell Netware,
additional software must be purchased to use the
machine as an FTP, Telnet, or Web server
Some UNIX commands
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man
date
ls
cat file
cd
cp
rm
mv
mkdir
rmdir