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 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 man date ls cat file cd cp rm mv mkdir rmdir wjo vi file chmod rights file startx exit