Unix NotesI. Unix HistoryII. Unix IntroductionIII. There are 2 pieces to the Unix os: Kernel and the ShellIV. Unix CommandsSome general interface issues:Accessing our Unix server:Logging on to an accountExiting a session.Basic command structure: Basic Keyboard manipulationsFiles:Directories:Users and Groups:V. Finding out about our environment!!!!!First things first: getting helpWho’s logged on and what are they doing?Information about a specific user:What processes are running?Unix NotesFall 2002Week (2)I. Unix History1960's AT&T developed MULTICS - a multi-user operating system.1969 AT&T Bell Labs - Unix system starts.Ken Thompson supported by Rudd Canaday, Doug McIlroy, Joe Ossana and Dennis Ritchie, wrote a small general purpose time-sharing system which started to attract attention. (PDP-7)1970 Assembler based Unix system ported to PDP-11.1972 Dennis Ritchie develops the C language. 1973 4th edition of Unix - the kernel and shell are rewritten in C. Group created at Bell Labs for internal support. 25 systems. First unofficial distribution to universities.1974 5th edition officially available to universities for educational purposes only. AT&T provides no support, no trial period, no warranty, no bug fixes and customer MUST pay in advance. Thus, in the mid-1970's, the Unix system was licensed to universities and gained a wide popularity in the academic community. because:- It was small, early systems used a 512K byte disk.- It was flexible. The source was available written in a high level language, which promoted portability of the OS- It was cheap. Universities were able to receive a Unix system license for the priceof a tape.Disadvantages at the time:- It had no support. AT&T had spent resources on MULTICS and wasn't interested in pursuing the Unix OS- It was buggy. No support - no fixes- It had little or no documentation - but you did get the source code.1975 Thompson attends University of California at Berkeley on sabbatical. Berkeley development starts. Supported by DARPA (?????), the developers could add a lot more features. BSD Unix.1977 500 systems mostly at universities. 1 BSD developed on PDP-11. First ports to non-DEC equipment.1980 4.0 BSD caught the eye of DARPA who was looking for a non-proprietaryOS standard for networked research systems for CAD/CAM, AI and vision applications. Berkeley’s virtual memory development more advanced that AT&T's. 1983 System V Release 1 - AT&T announces official support. The AT&T Unix has added many features of BSD Unix.1984 Consent decree lifted, Bell divestiture - allows AT&T to compete in the computer business.1987 750,000 Unix systems1988 Open Software Foundation founded - an independent company formed to develop and provide a computing environment that is based on industry standards and thebest technologies that are available.Today Unix is one of the front runners in the OS race. POSIX (Portable OS Interface for computer environments) trying to combine the best features of System V Unix and BSD Unix, into a standard. There is NO standard, so Each Unix is tailored by the manufacturer to better run on it’s hardware so each individual flavor. ULTRIX, SCO Unix, Lynex, HPUnix, although the basic command line interface is consistent throughout II. Unix IntroductionUnix as an OS has some decided advantages and disadvantages:Advantages- time sharing OS: can support multiple users running multiple tasks, Sharing resources between these users.- interactive, flexible operating interface- users can run multiple processes concurrently and switch between them.- support multiple users to facilitate the sharing of data between project member- When installing Unix, you only need to install the pieces relevant to your needs.- Provides security features that allow individual users to determine how their files are shared with others.Disadvantages- Interface can be difficult for a novice user to understand.III. There are 2 pieces to the Unix os: Kernel and the ShellThe Kernel is the operating system: - ultimately executes commands- it is responsible for managing the available resources and access to the hardware.- Contains modules for each hardware component that it interfaces with.- As new types of hardware are installed on the system, new modules can be incorporated into the kernel. The shell(s) is an interactive command interpreter. - Commands are entered at the shell prompt and acted upon as they are issued. - Users communicate with the computer through the shell. - The shell is NOT the kernel it translates commands into a form the OS can understand and ships them to the kernel for execution.- Commands can be either implemented as part of the shell itself, or stored as system programs.Many different shells: Examples of shells:Bourne Shell (sh) - original shell on AT&T based UnixC shell (csh) - shell developed at University of California Berkeley. Provided on BSD machines (syntax of shell scripts is similar to C)A derivative of csh is tcsh or T shell Korn Shell – derivative of the Bourne shell (sh) it is designed as an improvement featuring commands from both sh & cshIV. Unix CommandsSome general interface issues:- In its basic form: UNIX is a line oriented system similar to MS-DOS or VMS .- Each command is terminated by the “return” or “enter” key- UNIX uses the ASCII character set and supports upper and lower case. In otherwords UNIX is case sensitive- UNIX does not support function keys. However most shells allow special functions to be invoked by using the control key. IE. An executing command canbe terminated by pressing CTRL – C, or ^c. What control keys are available vary from shell to shell- Some features in UNIX (– editors) take advantage of features of specific types of terminals. (delete key, arrows). Some times when you log on, your screen may be jumbled, you may not be able to use the arrow keys, or if you open a file in an editor it may not display/scroll properly. If this happens you may need to specify your terminal type at the beginning of your session. For remote access usually useDEC, vt100:Setenv TERM vt100Accessing our Unix server:The easiest method for accessing the departmental server is via the web, entering the URL boole.csee.wvu.eduLogging on to an accountThe first part of accessing UNIX is to (of course) log on:login:password:When you fill out an account application, the system administrator will assign you a loginuserid, and default password..Standard Rules for passwords: ¡ 8