Week 2

Review questions:

        How will you determine the nodename and OS version of your Unix 
        machine ?

        How will you print the current directory name ?

        How will you look up documentation for a command in Unix ?

        How will you determine who is logged into a Unix system ?

        What is the cmd "stty" used for ?

        Why is Unix a multitasking system ?

        Why is Unix considered "open" system ?

        Why is Unix defined as an Operating System ? 

Unix commands:

        Unix utilities/cmds  are programs (cmds) available in the system for
        your use. They are resident in the /etc/ /bin /usr/bin /sbin 
        directories

        Every command has  

                a name
                command options [ they are optional ]
                an output [ visual display of output or effect ]
                could take some input [ depends on the command ]
                could produce an error message

        A command resides in standard system directory

        /etc /bin /usr/bin /usr/local/bin /sbin are possible system
        directories where commands could reside.

        Most cmds have a man page.

Unix man page sections:

        1 - commands
        1M - maintenance commands
        2 - System calls
        3 and its subcategories - libraries
        4 - file formats
        5,6,7,8  - OS version dependent sections

Linux: Man page sections

        http://linux.die.net/man/

        Section 1
                user commands (introduction) 
        Section 2
                system calls (introduction) 
        Section 3
                library functions (introduction) 
        Section 4
                special files (introduction) 
        Section 5
                file formats (introduction) 
        Section 6
                games (introduction) 
        Section 7
                conventions and miscellany (introduction) 
        Section 8
                administration and privileged commands (introduction) 
        Section L
                math library functions 
        Section N
                tcl functions 



Unix Editor:

        "vi" is the most common Unix/Linux editor. It is mentioned as vim(1) 
        and vi(1) in most Unix systems. In some Unix systems it functions 
        well if two special shell variables VISUAL and EDITOR are set in your
        environment. vimtutor(1) is a tool that helps learn vi.

Unix directory structure:

        Unix systems have huge number of files organized within directories.

        Directory structure is hierarchical, anchored at "root" / directory.

        cd, pwd, mkdir, rmdir are some of the commands that are available
        for use with directories in the Unix system.