Frozen Fish 1: Amiga/FrozenFish-Apr94.iso/bbs/alib/d1xx/d199/csh.lha/Csh/shell.doc

Text File | 1989-03-31 | 39KB | 1,295 lines

        INSTRUCTIONS FOR SHELL Version: 3.02A 20-Dec-88
        ===============================================

  Contents
  --------

    O.    Changes over old versions
    I.    Description
    II.   Overview of Major features
    III.  Restrictions
    IV.   PIPES
    V.    Command Pre-processor
    VI.   Command Line Editing
    VII.  Function Keys
    VIII. Shell Commands
    IX.   Special Set Variables
    X.    Advanced Topics
    XI.   Example login file
    XII.  Example script file
    XIII. Default values
    XIV.  Why ARP ?

O.  Changes over old version
    ------------------------

New to 3.02A:

- New commands: fornum, forline, strleft, strright, strmid, strlen, exec.
- Improved commands: foreach, pri.
- New system variable _clinumber.
- You can now split long lines in source files (see source for details).
- window -q now lists also position of screens/windows, not only dimension.
- Since strings are handled directly from Shell with new commands,
  rpn is now used only for calculations; string commands are gone.
  However, now RPN is really usable.
- Changed rawgets() to fix some problems with function keys, multi-line
  editing and window resizing; also, fixed bug with ^E.
- cat now warns you if it can't find any file matching your pattern.
- Now uses DOS packets to get ptr to CLI window; this fixes a bug that
  caused problems if Shell was run on unactive windows.
- Fixed minor bugs (htype printed some more ASCII bytes, some commands
  returned random values, history didn't print CR's).
- Heavy mods to this file.

New to 3.01A:

- Fixed bug with strings: before it printed strings with lenght 1 more
  than specified lenght.
- Made some additions and corrected many errors in Shell.doc (this file).
- Modified handler of external commands to allow things like DATE "?"
  (always use quotes).
- Corrected cat: it didn't work with STDIN before.

I.  Description
    -----------

This version of Shell is the follow of:
    Shell V2.04 (C)Copyright 1986, Matthew Dillon, All Rights Reserved
    Shell V2.04M-V2.07M by Steve Drew
    Shell V2.08MI and V3.xxA by Carlo Borreo & Cesare Dieni

Send suggestions/criticism/anything else to Carlo Borreo or Cesare Dieni at:

    BITNET:  [e-mail]

or
    Carlo Borreo        Cesare Dieni
    Via G. Berio 34        Via G. Taddei 3
    I-18100 Imperia        I-56100 Pisa
    Italy            Italy

For older version: Steve Drew at:

        ENET:    CGFSV1::DREW
        ARPA:    [e-mail]
        USENET:  {decvax|decwrl}!cgfsv1.dec.com!drew

or
        52 Castledale Cres N.E.
        Calgary, Alberta
        Canada

You may distribute this program for non-profit only.


II. OVERVIEW
    --------

Shell provides a convient AmigaDos alternative command interface.
All its commands are internal and thus does not rely on the c:
commands for any functionality.

Major features include:

    -command line editing
    -shell & Amigados search path support
    -simple history
    -redirection of any command
    -piping
    -aliases
    -variables & variable handling (embedded variables)
    -file name expansion via conventional wild carding ('?', '*' and more)
    -conditionals (if/else ect..)
    -source files  (w/ gotos and labels)
    -many built in commands to speed things up


III. RESTRICTIONS
     ------------

    o AmigaDos execute command will not work. Alternative is to use shell
      own script language (which is more powerful) or to do a 'run execute'.
    o This version runs UNDER WORKBENCH 1.2 or 1.3.
    o VDK handler has a bug with setting file dates so when using the copy
      command and VDK you should use the -d switch otherwise your file date
      in vdk: will be bad. (This is not a bug with shell)
    o If using with conman it may be best to start shell with the -a switch
      (shell -a .login) to turn off shell's command line editing and use
      conmans instead.


IV. NOTES ON PIPES
    --------------

    PIPES have been implimented using temporary RAM: files.  Thus, you
    should be careful when specifying a 'ram:*' expansion as it might
    include the temp. files.  These files are deleted on completion of
    the pipe segment.

    The file names used are completely unique, even with multiple shell
    running simultaniously.

    My favorite new feature is the fact that you can now redirect to and
    from, and pipe internal commands.  'echo charlie >ram:x', for
    instance.  Another favorite:

       echo "echo mem | shell" | shell

    To accomplish these new features, I completely re-wrote the command
    parser in execom.c

    NO BCPL program should be output-append redirected (>>).


V.  COMMAND PRE-PROCESSOR
    ---------------------

    Preprocessing is done on the command line before it is passed on to
    an internal or external routine:

    ^c    where c is a character is converted to that control character.
        Thus, say '^l' for control-l.

    $name    where name is a variable name.  Variable names can consist of
        0-9, a-z, A-Z, and underscore (_).  The contents of the
        specified variable is used.  If the variable doesn't exist,
        the specifier is used.  That is, if the variable 'i' contains
        'charlie', then '$i' -> 'charlie'.  If the variable 'i' doesn't
        exist, then '$i'->'$i' .

    ;    delimits commands.   echo charlie ; echo ben.

    ' '    (a space). Spaces delimit arguments.

    "string" a quoted string.  For instance, if you want to echo five spaces
        and an 'a':

        echo      a       -> a
        echo "    a"      ->      a

    \c    overide the meaning of special characters.  '\^a' is a
        circumflex and an a rather than control-a.  To get a backslash,
        you must say '\\'.

        also used to overide alias searching for commands.

    >file    specify output redirection.  All output from the command is
        placed in the specified file.

    >>file    specify append redirection (Does not work with BCPL programs).

    <file    specify input redirection. The command takes input from the
        file rather than the keyboard (note: not all commands require
        input; it makes no sense to say 'echo <charlie' since
        the 'echo' command only outputs its arguments).

    |    PIPE specifier.  The output from the command on the left becomes
        the input to the command on the right.  The current SHELL
        implimentation uses temporary files to store the data.

    !!    execute the previously executed command.
    !nn    (nn is a number).  Insert the history command numbered n (see
        the HISTORY command)
    !partial search backwards through the history list for a command which
        looks the same as 'partial', and execute it.

    #    Enter comment.  The rest of the line is discarded (note: \#
        will, of course, overide the comment character's special
        meaning)


VI. COMMAND LINE EDITING
    --------------------

    o Command line can be upto 255 chars.
    o Inserts and deletes are handled correctly over multiple screen lines.
    o Shell will keep track of the line width should the window get resized.

    KEY DEFINITIONS:
        Up Arrow    Recal previous commands
        Down Arrow  Recal commands
        Left Arrow  Move cursor about command line.
        Right Arrow  "     "      "      "      "
        Shift-Up Arrow    Get start of history
        Shift-Down Arrow   "  end   "     "
        Shift-Left Arrow  Moves cursor a bit left
        Shift-Right Arrow   "     "    "  "  right
        ^A        Toggle insert/overtype mode.
        ^D        EOF
        ^E        Put cursor at end of text.
        ^K        Delete to end of line.
        ^R        Retype current line.
        ^U        Erase entire line.
        ^X        Erase entire line.
        ^Z        Put cursor at start of text.
        f1 - f10    Execute command if variable exists.
        F1 - F10    More commands (Shifted f keys).
        Help        Invokes help command


VII. FUNCTION KEYS
     -------------

    Function keys now insert text to the current position on the command
    line. They maybe terminated with a ^M (return). f1 would be non shifted
    where as F1 is shifted.
    Most of functions key have a default definition, but it may be changed.

      $ set f1 dir df0:^M

    will add the text 'dir df0:<return>' to the current line.

      $ set f1 dir

    would only add 'dir' you could then enter ' df0:<return>'


VIII. SHELL COMMANDS
      ---------------

   First to start shell from a CLI

   shell [-a] [-c command;command]

   where:
    -a disables all command line editing features. This is useful for
    when running shell over AUX:, and necessary if you are running
    CONMAN.

    -c allows execution of one command line and then exits out of shell.
    This is useful for running a internal shell commands in the
    background or from an external application. eg:

        Run shell -c dir df0:; copy -r df0: df1: >nil:; echo "Done"

    If you 'Run' shell in the background without the -c switch shell
    will detect this and imediatley exit.

   Command execution:

   Internal shell commands maybe abreviated.

   The first argument is the command-name... here is (in order) how Shell
   tries to execute it:

    1) Alias list is searched for an alias exactly matching name.
    2) Internal commands list is scanned for a command even partially
       matching name (so you can, for instance, say resi for resident;
       however, you should specify enough of a command to be unique).
    3) ARP resident list is scanned (you can use Shell's resident
       command to add/remove a file in this list).
    4) At this point, command is supposed to be external (disk), and
       is searched before in current directory, then in Shell's
       path, and finally in AmigaDOS path.
    5) As a last chance, AUTOMATIC SOURCING is tried.

   AUTOMATIC SOURCING may be accomplished by naming shell scripts with a
   .sh suffix.  Thus, if you say 'stuff' and the file 'stuff.sh' exists in
   your current or C: directory or anywhere in Shell search path, it will
   be SOURCED with any arguments you have placed in the $_passed variable.
   This is equivalent to typing 'source stuff.sh'

   Wild card expansions:
    Most shell commands will accept multiple arguments that can
    be as a result of wild card expansion. Also when the calling
    an external command shell will first expand any wild cards
    to seperate arguments. If you wish to have the external command
    handle it's own wild carding you will need to insert quotes
    around the special wild card characters ? and *.

    eg.
        arc a new.arc *.txt    - shell will expand and pass to arc
        arc a new.arc "*.txt"    - let arc expand the wild cards.

    Wild card expansions:

    ?    match any single character
    *    match any string
    .../*    recursive search down ALL sub directories from current level
    !    Exclude pattern matching specifier
    &    prefixed to patterns, ask confirmation for each file

    Examples:

    df0:.../*        all files in all directories on df0:
    df0:.../!*.info     full directory tree of df0: but exclude
                any ugly .info files.
    !*.o !*.c        will result in ALL files matching since what
                doesn't match the !*.o will match the !*.c
    df1:&*            all files in root of df1:, but ask
                confirmation for each

    LIST OF COMMANDS:
    -----------------

    ABORTLINE
    Usage    : abortline
    Example    : echo a;abort;echo b
    Results    : a

    Causes the rest of the line to be aborted. Intended for use in
    conjunction with exception handling.

    ADDBUFFERS
    Usage    : addbuffers drive buffers
    Example    : addbuffers df0: 24

    Just like AmigaDOS addbuffer command, causes new buffers to be
    allocated for disk I/O. Each buffer costs 512 bytes of CHIP memory.

    ALIAS
    Usage    : alias [name [command string] ]
    Example    : alias vt "echo Starting VT100;run sys:tools/vt100"

    Sets a name to be a string. You can alias a single name to a set
    of commands if you enclose them in quotes as above. By simply
    typing vt, the command line above would be executed.

    Argument Passing to an Alias:

    Usage    : alias name "%var [command string]"
    Example    : alias xx "%q echo hi $q, how are ya."
          xx Steve
    Results    : hi Steve, how are ya.

    The second form of the alias command allows passing of arguments
    to any position within the command string via use of a variable
    name. To pass arguments to the end of a command string this method
    is actually not necessary.

    Typing "alias name" you will get the alias for that name, while with
    "alias" you get a list of all alias.

    ASET
    Usage    : aset name value
    Example    : aset INCLUDE include:

    Set a variable in a way that is compatible with Aztec SET command;
    this is completely different from Shell variable.
    May even be used to set ARP variables.

    ASSIGN
    Usage    : assign [logical [physical] ]
    Example    : assign C: df1:c

    Use it like AmigaDOS assign command to set, remove or list
    assignments of logical names to directories.

    CAT
    Usage    : cat [-n][file file....]
    Example    : cat foo.txt

    Type the specified files onto the screen.  If no file is specified,
    STDIN in used.  CAT is meant to output text files only.
    Specifying -n option you will get numbered lines.

    CD
    Usage    : cd [path]
    Example    : cd df0:devs/printers

    Change your current working directory.  You may specify '..' to go
    back one directory (this is a CD specific feature, and does not
    work with normal path specifications).

    CD without any arguments displays the path of the directory you
    are currently in.

    CLOSE
    Usage    : close filenumber

    Close the specified file opened by open.
    See open and flist for more info.

    COPY
    (CP)
    Usage    : copy [-u][-d] file file
    or    : copy [-u][-d] file1 file2...fileN dir
    or    : copy [-r][-u][-d] dir1 dir2...dirN dir
    options    :
        -r    recursive, copy all subdirectories as well.
        -u    update, if newer version exist on dest, don't copy
        -d    don't set destination file date to that of source.

    Example    : copy -r df0: df1:

    Copy files or directories. When copying directories, the -r option
    must be specified to copy subdirectories as well.  Otherwise, only
    top level files in the source directory are copied.

    All files will be displayed as they are copied and directory's
    displayed as they are created. This output can be suppessed by
    redirecting to nil: eg. copy -r >nil: df0: df1:

    Copy will abort after current file on Control-C.

    Copy by default sets the date of the destination file to that of
    the source file. To overide this feature use the -d switch.

    Another useful option is the -u (update) mode were copy will not
    copy any files which exists already in the destination directory
    if the destination file is newer or equal to the source file.
    This is useful when developing code say in ram: eg. 'copy *.c ram:'
    when done you can copy -u ram: df1: and only those modules you have
    modified will be copied back.

    Copy command will now create the destination directory if it does
    not exist when specified as 'copy [-r] dir dir'. If you specify
    copy file file file dir, then 'dir' must already exist.

    CP
    Equivalent to copy.

    DATE
    Usage    : date [new date and/or time]
    Example    : date Wednesday  # this refers to NEXT wed, of course

    Used to read or set system date and/or time. All standard options
    may be used (yesterday, tomorrow, monday, etc.).
    Leading zero's are not necessary.
    Without parameters shows Dddddd DD-MMM-YY HH:MM:SS.

    DEC
    Usage    : dec varname [value]
    Example    : dec abc

    Decrement the numerical equivalent of the variable with specified
    value (default: 1) and place the ASCII-string result back into
    that variable.

    DELETE
    (RM)
    Usage    : delete [-p][-r] file file file...
    Example    : delete foo.txt test.c

    Remove (delete) the specified files.  Remove always returns
    errorcode 0.  You can remove empty directories.  The '-r' option
    will remove non-empty directories by recursively removing all sub
    directories.
    You can remove delete-protected files specifying -p option.
    If you specify any wildcard deletes the files will be listed as
    they are deleted. This can be suppressed by redirecting to nil:

    DIR
    (LS)
    Usage    : dir [-sdf] [path path ... ]
    Example    : dir df0:
    options    :
        -s  short multi(4) column display.
        -d  list directories only
        -f  list files only

    Displays a directory of specified files. Default output shows
    date, protection, block size, byte size and total space used.
    Protections flags include new 1.2/1.3 flags (see under protect).
    Files are alphabetically sorted, without case sensitivity, and
    directories are always in red pen.

    DISKCHANGE
    Usage    : diskchange drive

    Like AmigaDOS diskchange.

    ECHO
    Usage    : echo [-n] string
    Example    : echo hi there
    Results    : hi there

    Echo the string given. If -n switch given no newline is
    appended.

    ELSE ;
    Usage    : else ; command
    Usage    : if -f foo.c ; else ; echo "Not there" ; endif

    Else clause, must follow an IF statement.

    ENDIF
    Usage    : endif

    The end of an if statement.

    Note: if you return from a script file with unterminated IF's
    and the last IF was false, prompt will be changed to an
    underscore ('_') and no commands will be executed until
    'endif' is typed.

    EXEC
    Usage    : exec command
    Example    : set util SYS:sytem/utilities
          exec $util/make    # would not work without exec

    Execute the command specified; exec command is equivalent to
    command, only you can use variables to specify command name.

    FAULT
    Usage    : fault error1 .. errorN
    Example    : fault 205 212

    Like AmigaDOS fault, prints specified error messages.

    FILENOTE
    Usage: filenote file1 .. filen  note

    Set AMIGADOS comment of the specified file. This is not very useful,
    since in current implementation of Shell file comments are not listed
    in directory, but it was so easy to implement...

    FLIST
    Usage    : flist

    Lists the filenumbers of files opened by open.
    See open and close for more info.

    FOREACH
    Usage    : foreach [-v] varname ( strings ) command
    Example    : foreach i ( a b c d ) "echo -n $i;echo \" ha\""
    Result    : a ha
          b ha
          c ha
          d ha

    'strings' is broken up into arguments.  Each argument is placed in
    the variable 'varname' in turn and 'command' executed.  To execute
    multiple commands, place them in quotes.

    Foreach is especially useful when interpreting passed arguments in
    an alias.

    eg.
        foreach i ( *.pic ) viewilbm $i
    assuming a.pic and b.pic in current directory the following commands
    will occur:
        viewilbm a.pic
        viewilbm b.pic

    Flag -v causes arguments to be displayed every time command is
    executed.

    FOREVER
    Usage    : forever command
    or    : forever "command;command;command..."

    The specified commands are executed over and over again forever.

    -Execution stops if you hit ^C
    -If the commands return with an error code.

   FORLINE
    Usage    : forline var filename command
    or    : forline var filename "command;command..."
    Example    : forline i RAM:temp "echo line $_linenum=$i"

    For each ASCII line of file specified commands are executed and
    var points to line content. You can check system variable _linenum
    to find the number of the line currently read.

   FORNUM
    Usage    : fornum var n1 n2 command
    or    : fornum var n1 n2 "command;command..."
    Example    : fornum x 1 10 echo $1

    Executes command(s) for all numerical values of x between n1 and n2.

   GOTO
    Usage    : goto label
    Example    :
          label start
            echo "At start"
            dir ram:
            goto start

    Goto the specified label name.  You can only use this command from a
    source file. Labels may now be forward or reverse from current
    position.

    HELP
    Usage    : help
    Example    : help

    Simply displays all the available commands.  The commands are
    displayed in search-order.  That is, if you give a partial name
    the first command that matches that name in this list is the one
    executed.  Generally, you should specify enough of a command so that
    it is completely unique.

    HISTORY
    Usage    : history [partial_string]
    Example    : history

    Displays the enumerated history list.  The size of the list is
    controlled by the _history variable.  If you specify a partial-
    string, only those entries matching that string are displayed.

    HOWMANY
    Usage    : howmany

    This command tells you how many instances of Shell are running
    in your system.

    HTYPE
    Usage    : htype file1 .. filen

    Displays the specified files in hex and ASCII, just like the system
    command Type file opt h. Especially suitable for binary files.

    IF
    Usage    : if [-n] argument conditional argument ;
    or    : if [-n] argument
    or    : if [-n] -f file
    or    : if [-n] -d file/dir
    or    : if [-n] -m
    or    : if [-n] -t file file1 .. fileN
    or    : if [-n] -r rpnexpression

    If a single argument is something to another argument.  Conditional
    clauses allowed:

    <, >, =, and combinations (wire or).  Thus <> is not-equal, >=
    larger or equal, etc...

    If arguments are not numeric, they are compared as strings.

    Usually the argument is either a constant or a variable ($varname).

    The second form if IF is conditional on the existance of the argument.
    If the argument is a "" string, then false , else TRUE.

    The third form of IF used by -f switch checks for existance of
    the specified file.

    Switch -d tests the type of the object specified: if it is a
    directory, then TRUE; if it is a file (or it doesn't exist)
    then FALSE.

    Switch -m is used to test if FAST memory is present, i.e. wheter
    more than 512K RAM are available.
    Example (to be included in a login.sh file):
    if -m; resident -a as ln cc; endif

    Using -t form compares the date and time of the first file with
    all the others; if the first is younger than ALL the others, then
    FALSE, else TRUE. If a file doesn't exists, it is considered as
    being older.
    This feature is especially useful for building makefiles without
    using any MAKE utility.
    Example:
    if -t test.o test.asm test.i ; asm -o test.o test.asm ; endif

    Option -r evaluates a given RPN expression (see under RPN for more
    info): if value on top of stack is 0, then FALSE, else TRUE.

    Switch -n (NOT) reverses the result.

    When using 'IF' command interactively if you are entering commands
    following an 'IF' that was false, the prompt will be set to a
    underscore '_ ' to indicate all commands will be ignored until
    an 'ELSE' or 'ENDIF' command is seen.

    INC
    Usage    : inc varname [value]
    Example    : inc abc 5

    Increment the numerical equivalent of the variable with specified
    value (default: 1) and place the ascii-string result back into
    that variable.

    INFO
    Usage    : info

    Display Device statistics for all the disk-type devices in system
    (DFk:, HDk, JHk:, RAM:, RDk: ...), just like the system command
    info. Gives block used/free, % used, errs, status and volume name.

    INPUT
    Usage    : input var var ... var
    Example    : input abc

    Input from STDIN (or a redirection, or a pipe) to a variable.  The
    next input line is placed in the variable.

    JOIN
    Usage    : join [-r] file1..fileN destfile
    Example    : join part1 part2 part3 total

    Joins the specified files to get destfile. If destfile already
    exists, an error message is generated and operation is aborted,
    unless you specify -r (replace) option.

    LABEL
    Usage    : label name

    Create a program label right here. Used in source files, can then
    GOTO a label.

    LS
    Equivalent to dir.

    MD
    Equivalent to mkdir.

    MEM
    Usage    : mem

    Display current memory statistics for CHIP memory and
    FAST memory (if any installed).

    MKDIR
    (MD)
    Usage    : mkdir name name name...
    Example    : mkdir df0:stuff

    Create the specified directories.

    MV
    Equivalent to rename.

    OPEN
    Usage    : open filename filemode filenumber
    Example    : open RAM:data w 1

    This allows you to open a file, redirect to it as many commands
    as you like, then close it.
    Filename is any valid AmigaDOS filename, filemode is either r
    for read or w for write, filenumber is a number between 1 and 10.
    To redirect a program to or from an open file, use as your redir
    filename a dot followed by the filenumber.
    Here is a complete example:

        open RAM:data w 1
        echo -n 2+2= >.1
        rpn 2 2 + . CR >.1
        close 1
        type RAM:data    # will display 2+2=4
    See also close, flist.

    PATH
    Usage    : path

    Used to list AmigaDOS path. In current version can't be used to
    set it.

    PRI
    Usage    : pri clinumber pri
    Example    : pri 3 5    # set priority of cli #3 to 5

    Change the priority of the specified task (use PS command to
    determine clinumber). If you specify 0 as clinumber you can
    change priority of "this" task (the one executing shell).

    PROTECT
    Usage    : protect file1 ... filen [flags]
    Example    : protect myfile rwe

    Set AMIGADOS file protection flags for the file specified. Valid
    flags are h, s, p, a, r, w, e, d.
    If you don't specify the flags, all flags are cleared.
    Bit 'a' is new to WorkBench 1.2, while 'h', 's', 'p' are new to 1.3.

    PS
    Usage    : ps

    Gives status of DOS processes.  eg:

    Proc Command Name    CLI Type    Pri.  Address  Directory
     1   SHELL        Initial CLI   0      97b0  Stuff:shell
     2   sys:c/clockmem    Background  -10    2101a8  Workdisk:
     3   c:emacs        Background    0    212f58  Stuff:shell
     4   sys:c/VT100    Background    0    227328  Workdisk:

    Address is the addres of the task, directory is the process
    currently CD'd directory.

    PWD
    Usage    : pwd

    Rebuild _cwd by backtracing from your current directory.

    QUIT
    Usage    : quit

    Quit out of Shell back to CLI.

    RBACK
    Usage    : rback command

    Start a new process executing the specified command, but can't do
    input/output. Equivalent to 'run command >NIL: <NIL:'.
    This command is not fully reliable: use at your own risk.

    RENAME
    (MV)
    Usage    : rename from to
    or    : rename from from from ... from todir

    Allows you to rename a file or move it around within a disk.
    Allows you to move 1 or more files into a single directory.

    RESIDENT
    Usage    : resident [-a][-r] [files]

    This is ARP resident. Commands are searched by Shell in resident
    list BEFORE of searching on any external device.
    Option -a loads RESIDENT programs, -r removes them.
    Resident with no args lists resident programs.
    Not all programs can run as resident, see ARP docs for more info.

    RETURN
    Usage    : return [n]
    Example    : return 10

    Exit from a script file, or quit from shell with optional
    exit code.

    RM
    Equivalent to delete.

    RPN
    Usage    : rpn expression
    Example    : rpn 3 7 *    # Prints the value 21

    Evaluate an RPN expression, using 32-bit values. In older versions
    of Shell RPN contained string functions too, but now that strings
    are handled by specifical commands, these are no more needed.
    At end of evaluation, RPN prints values on stack, so you can
    say for instance "rpn $x 2 * | input x" to double the value of
    variable x.
    Functions implemented are:

        + - * /    Obvious meaning; / means integer division, of course
        %        Module operator e.g. "rpn 7 3 %" answers 1
        & | ~    Bitwise and, or, not operators
        > < ==    Tests for greater-than, lower-than, equal. To get
            a test for >= (or <=), you can use < ! (or > !)
        !        Logical not operator
        DUP        Duplicate value on top of stack
        DROP    Drop value on top of stack
        SWAP    Swap two values on top of stack

    RUN
    Usage    : run prgm args
    Example    : run emacs test.c

    Start a new process executing the specified command.
    In current implementation run command can't be redirected.
    This command is not fully reliable: use at your own risk.
    See also rback.

    SEARCH
    Usage    : search [-w][-c][-n][-r][-e][-q] filelist string

    Search specified files for a string. Only lines containing the
    specified strings are displayed.

    If you specify any directory in filelist, and use the -r (recurse)
    switch, all files in directory are recursively searched.

    Lines are numbered for default; use -n (number) switch to turn off
    line numbering.

    Search is normally not case sensitive; use -c (case) flag to turn ON
    case sensitivity.

    By specifying -e (exclude) switch, only lines NOT containing the
    specified string are listed.

    Using -w (wild) flag, only the lines matching with the string are
    listed.
    Notes to wild card matching;
    - Uses Shell standard matching.
    - Wild cards allowed are *, ?, !.
    - Matching is not case sensitive (even if you use -c flag).
    - The WHOLE line must match the string, not only a substring.
    - String MUST be enclosed in quotes to avoid wildcard expansion

    Flag -q (quiet) suppresses printing of file names.

    Examples:
        search -c -r df0:include ACCESS
    Find all occurrencies of ACCESS (in uppercase) in all files
    contained in include directory.
        search -w shell.h "#define*"
    Lists only lines of file beginning with (not simply containing)
    #define.

    SET
    Usage    : set [name] [string]
    Example    : set abc hello

    Set with no args lists all current variable settings.
    Set with one arg lists the setting for that particular variable.
    Specifying name and string, stores the string into variable name.

    Also See the section on special _variables.


    SLEEP
    Usage    : sleep timeout
    Example    : sleep 10

    Sleep for 'timeout' seconds, or until ^C typed.

    STACK
    Usage    : stack [number]
    Example    : stack 8000

    Changes the default stack for this CLI. Without arguments, prints
    it.

    STRHEAD
    Usage    : strhead varname breakchar string
    Example    : strhead j . foobar.bas
          echo $j
    Result    : foobar

    Remove everything after and including the breakchar in 'string' and
    place in variable 'varname'.

    STRINGS
    Usage    : strings file1..fileN minlenght
    Example    : strings c:dir c:list shell 7

    Prints strings contained in specified files (usually binary)
    with lenght >= minlenght.

    STRLEFT
    Usage    : strleft varname string n
    Example    : strleft x LongString 5    # Will set x to "LongS"

    Place leftmost n chars of string in variable varname.

    STRLEN
    Usage    : strlen varname string
    Example    : strlen x Hello    # Will set x to "5"

    Puts len of string in variable varname.

    STRMID
    Usage    : strmid varname string n1 [n2]
    Example    : strmid x LongString 5 3    # Will set x to "Str"

    Places n2 chars from string, starting at n1, in variable varname.
    By omitting n2, you get all chars from n1 to end of string.

    STRRIGHT
    Usage    : strright varname string n
    Example    : strright x LongString 5    # Will set x to "tring"

    Place rightmost n chars of string in variable varname.

    STRTAIL
    Usage    : strtail varname breakchar string
    Example    : strtail j . foobar.bas ; echo $j
    Result    : bas

    Remove everything before and including the breakchar in 'string' and
    place in variable 'varname'.

    SOURCE
    Usage    : source file [arguments]
    Example    : source mymake.sh all
    Result    : source file 'mymake.sh' called with var _passed = 'all'

    Execute commands from a file.  You can create SHELL programs in
    a file and then execute them with this command.  Source'd files
    have the added advantage that you can have loops in your command
    files (see GOTO and LABEL).  You can pass SOURCE files arguments
    by specifying arguments after the file name.  Arguments are passed
    via the _passed variable (as a single string).

    Long lines may be split by appending a backslash (\) at end of
    first half. However, even joined lines cannot be longer than
    ~255 chars. See example of source files.

    Automatic 'sourcing' is accomplished by placing a .sh extension on
    the file and executing it as you would a C program:

    --------- file hello.sh ---------
    foreach i ( $_passed ) "echo yo $i"
    ---------------------------------

    $ hello a b c
    yo a
    yo b
    yo c

    TYPE
    Equivalent to CAT.

    TOUCH
    Usage    : touch file1 .. fileN

    Sets DateStamp on the specified files to the current date and time.

    UNALIAS
    Usage    : unalias name .. name
    Example    : unalias vt

    Delete aliases..

    UNSET
    Usage    : unset name .. name
    Example    : unset abc

    Unset one or more variables.  Deletes them entirely.

    VER
    Usage    : ver

    Show current version name, & authors.

    WINDOW
    Usage    : window [-q][-f][-b][-l][-s] [dimensions]
    Options    :
        -f    (front) Window to front
        -b    (back)  Window to back
        -l    (large) Window to maximum size
        -s    (small) Window to minimum size
        -a    (activate)
        -q    (query) Lists screens and windows open

    Various operations on CLI window. If dimensions are specified,
    they must be in the form x y width height, with values separated
    by spaces.
    The command "window -l" may be very useful on PAL machines to
    get a full PAL window from your login sequence, or if you use
    overscan WorkBench.
    Option -q gives, for each Screen and Window currently open,
    title, left edge, top edge, width, height.


IX. SPECIAL SET VARIABLES
    ---------------------

    _prompt
    This variable is set to the string you wish printed as your
    prompt. This can contain escape sequences if you wish, or
    you can include a %p in path definition to get CD in your
    prompt.
    Default prompt shows path specification in red pen, followed by
    a greater (>) sign and a space.
    The if command will set the prompt to a '_ ' if commands are
    disabled while waiting for a 'endif' or 'else' command. Interactive
    mode only.

    _history
    This variable is set to a numerical value, and specifies how far
    back your history should extend.

    _debug
    Debug mode... use it if you dare.  must be set to some value

    _verbose
    Verbose mode (for source files).  display commands as they are
    executed.

    _maxerr
    The worst (highest) return value to date.  To use this, you usually
    set it to '0', then do some set of commands, then check it.

    _lasterr
    Return code of last command executed.  This includes internal
    commands as well as external comands, so to use this variables
    you must check it IMMEDIATELY after the command in question.

    _cwd
    Holds a string representing the current directory we are in from
    root.  The SHELL can get confused as to its current directory if
    some external program changes the directory.  Use PWD to rebuild
    the _cwd variable in these cases.

    _passed
    This variable contains the passed arguments when you SOURCE a file
    or execute a .sh file.  For instance:

    test a b c d

    -------- file test.sh ----------
    echo $_passed
    foreach i ( $_passed ) "echo YO $i"
    --------------------------------

    _path
    This variable contains the search path when the shell is looking
    for external commands.  The format is:  DIR,DIR,DIR  Each DIR must
    have a trailing ':' or '/'.  The current directory is always
    searched first.  The entire path will be searched first for the
    <command>, then for <command>.sh (automatic shell script sourcing).

    The default _path is set to
        ram:,ram:c/,df0:c/,df1:c/,df0:,df1:,sys:system/

    _insert
    Sets the default for insert/overtype mode for command line
    editing. ^A toggles between, but after <RET> the default is
    set back as indicated by this variable. By default _insert is 1
    indicating insert mode on setting to zero will make overtype
    the default.

    _titlebar
    Used to set window's title bar.

    _clinumber
    Contains the number (1-20) of current CLI.

X.  ADVANCED TOPICS
    ---------------

    EXCEPTION_PROCESSING:

    if no _except variable exists, any command which fails causes the
    rest of the line to abort as if an ABORTLINE had been executed.  If
    the _except variable exists, it is of the form:

    "nnn;commands..."

    where nnn is some value representing the minimum return code required
    to cause an error.  Whenever a command returns a code which is
    larger or equal to nnn, the commands in _except are executed before
    anything.  WHEN _except EXISTS, THE COMMAND LINE DOES NOT ABORT
    AUTOMATICALLY.  Thus, if you want the current line being executed
    to be aborted, the last command in _except should be an "abortline".

    exception handling is disabled while in the exception handling routine
    (thus you can't get into any infinite loops this way).

    Thus if _except = ";", return codes are completely ignored.

    example:

    set _except "20;abortline"

XI. EXAMPLE LOGIN FILE
    ------------------

If from a CLI or the startup-script you say 'SHELL filename', that file is
sourced first.
If you are a CLI user, your startup-sequence may be as simple as:

    C:Shell S:login.sh

Here is, my startup code:

### Example S:login.sh ###

window -l    # if you are on a PAL machine, or use overscan

set _prompt ^[[33m[$_clinumber].%p>" "

set F5 "cdir WORK:"^M
set f9 "ed s:login.sh"^M
set F9 "ed df0:s/startup-sequence"^M
alias toram  "%q foreach i ( $q ) \"cp -r $i: ram:$i >NIL:;\
    assign $i: ram:$i\""
alias ramop  "md RAM:op; assign OP: ram:op"
alias noop   "assign OP: ; rm -r ram:op"
alias newop  "rm -r OP:*"
alias dc     "dfc df0: to df1:"
alias go     "%q assign WORK: Boot:$q; cd WORK:; source startme.sh"
alias get    "%q cp $q RAM: >NIL:"

assign LC:    Stuff:c
assign INCLUDE:    Stuff:include
assign LIB:    Boot:lib
assign QUAD:    RAM:

rback C:FaccII; sleep 1
    # after spawning a process, it is always better to allow it
    # to load the command, to avoid excessive drive head movement

C:REZ Blink CC LC1 LC2 >NIL:

C:PopCli 300 C:Newcli
C:FF -1 Siesta.font >NIL:
C:Patch_1 >NIL:
stack 8000    # lc1 and lc2 need this

source S:setdate.sh    # this is listed in next chapter

### End of example login.sh ###


XII.  Example Source file
      -------------------

The following is an example source file to set date and time; it may be
used at startup if you don't have an internal clock.

### setdate.sh ###

open CON:200/100/440/80/SetDate write 1
echo >.1 -n "Current date is "
date >.1
echo >.1 -n "Please enter date: "
input <.1 d
close 1
strlen len $d
if -r $len 1 > ; date $d ; endif
echo -n "New date: " ; date

### End of setdate.sh ###

Next comes a makefile that needs no Make program: may be executed from
Shell directely!!!

### make.sh ###

if -t Shell.syms Shell.h; cc +HShell.syms Shell.h; rm shell.o; endif
if -t RAM:Shell.syms Shell.syms; cp -d Shell.syms RAM:; endif

foreach i ( main comm1 comm2 comm3 execom globals rawconsole run set \
 sub ) "if -t $i.o $i.c; echo Compile $i...;cc +IRAM:shell.syms $i.c; endif"

if -t Shell run.o main.o comm1.o comm2.o comm3.o execom.o \
set.o sub.o globals.o rawconsole.o
            ln  +q -m -o Shell run.o main.o comm1.o comm2.o comm3.o\
        execom.o set.o sub.o globals.o rawconsole.o -la -lc
endif

### End of make.sh ###


XIII.  Default Values
       --------------

To make things easier, some aliases are predefined whenever you start a
new Shell. These are:

    - cls
    Simply clear the screen.

    - cdir
    Use "cdir directory" to clear the screen, set CD to directory,
    and list it.

    - kr
    Deletes everything on RAM:. If you think this is dangerous,
    you can remove this alias.

    - exit
    Leave Shell and exit CLI.

Moreover, many variables have default values, and many function keys are
predefined. You can use set command to determine all of these.

XIV.  Why ARP ?
      ---------

For those of you curious enough, the A in "3.xxA" means ARP. The most
recent versions of Shell use ARP.library. This has been very useful in:

 - Implementing commands like ASET, ASSIGN, INFO, RESIDENT, RBACK, RUN.
 - Keeping executable code small.

ARP.library is really public domain, so one can include it in any package,
both commercial or public domain, like I am doing with Shell.
The ARP team is trying to wipe out the BCPL from AMIGA. This is a very
good idea, I think. And there is a lot of people hoping that Commodore
will put ARP.library in ROM, before or after. This would  make the AMIGA
a very mory friendly computer to use and program.
I encourage programmers to get ARP development package: you can find it
on many BBS, and is really public domain. Users can look for a replacement
of C: commands from ARP (but, of course, if you use this Shell you won't
need them anymore, except for ARUN).