SHELL(1)                         User Commands                         SHELL(1)

NAME
        shell - Spinix shell program

SYNOPSIS
        shell

DESCRIPTION
        Provides the command-line interface for the Spinix operating system.
        The shell program can execute the following commands:

            pwd     - print the current working directory
            cd      - change working directory
            echo    - echo the command line parameters
            FILE    - execute FILE

        Executable files can be one of the following:

            - Spinix Spin application
            - Spinix C application
            - Stand-alone C or Spin program
            - script file

        Spinix examines the first long of a file to determine what type of
        executable it is.  A Spin app contains "SPIN" and a C app contains
        "CAPP".  C apps must use the LMM memory model.

        A stand-alone C or Spin program is signalled by a clock frequency
        between 80 and 120 MHz.  Spinix will modify the clock frequency to
        match the current clock frequency when the stand-along program is run.
        It does not modify any other portion of the program.

        C and Spin programs must be less than or equal to 31.5K bytes since the
        spinix shared memory is located in the top 512 bytes of memory.
        Program files must consist of contiguous sectors, since the loader does
        not implement cluster chaining.  This can be ensured by using 32K
        clusters.

        Standard I/O can be redirected by using the ">", "<" and ">>" comand-
        line modifiers.

        The first line of a script file must start with "#shell".  Script file
        can call another script file up to 26 levels deep.

        Shell script files support the following commands:

            if     - conditionally execute based on following condition
            then   - must be on the next line after an "if" line
            fi     - terminates the body of an if statment
            while  - begin conditional loop based on following condition
            do     - must be on the next line after a "while" line
            done   - terminats the body of a while statement
            exit   - exit the script file

        An if statement may contain an executable file, such as

            if spinit file
                or
            if test $a -ne 0

        The if statement will test the return value from the executable file,
        which is referenced by $?.  A short-hand version of using test is to
        use bracket, so that the "if test" statement above can be written as

             if [ $a -ne 0 ]

        The shell allows defining variables using the "=" operator, such as

             a=123

        There must be no spaces before or after the equal.  Double quotes
        can be used to assign a value containing spaces, such as

             b="This is a test"

        Variables can be accessed by prepending a "$" character to the name.
        From the previous examples, a and b can be printed using echo by
        typing

             echo $a $b

        Spinix provides other variables, which are $?, $#, $1, $2, etc.
        $? contains the return value from the last program that has been
        executed.  $# contains the number of command-line parameters, and
        $1, $2, etc. contain the values of the command-line parameters.


LIMITATIONS

AUTHOR
        Dave Hein

COPYRIGHT
        Copyright (c) 2011, 2012, 2013, Dave Hein
        MIT License (See license.txt in the root directory)
        This is free software: you are free to change and redistribute it.
        There is no warranty, to the extent permitted by law.


SPINIX utility                    March 2012                           SHELL(1)