Oakland CPM Archive/oakcpm.iso/cpm/zcpr33/z33anote.0z2/Z33ANOTE.002

Text File | 1987-06-10 | 11.1 KB | 251 lines

                        ZCPR33 APPLICATION NOTES

Note Number:    002
Author:        Jay Sage
Date:        June 8, 1987


     Making Effective Use of ARUNZ as an Extended Command Processor
                 (Especially on a Remote Access System)


   From my recent experience using several ZCPR33 remote access systems,
most sysops are not aware of the way ARUNZ can be used as an extended
command processor to make the operation of their system much, much
easier for their users.  Because a single 4K ALIAS.CMD file can contain
hundreds of aliases, the cost in disk space to provide a highly error-
tolerant environment to the user is very small.  These techniques can
also be used to great advantage on a personal system to make the sytem
highly tolerant of errors.

     The kinds of aliases can be grouped loosely into three categories,
each of which I will cover below.  At the end I will describe a method
for making these aliases execute at top speed.


Alternate Command Forms
-----------------------

     The most obvious use of aliases is to provide alternative names for
commands.  We will use an example to illustrate the principle.  Consider
the task of finding out if a certain file is somewhere on the system and
where.  Some systems use FINDF, the original ZCPR3 program for this
purpose; others use one of the standard CP/M programs (WIS or WHEREIS);
and others have begun to use the new, enhanced ZSIG program called FF.
This can be very confusing to new users or to users who call many
different systems.  The solution is to provide aliases for all the
alternatives.  Suppose FF is the real program in use.  Then the
following line in ALIAS.CMD will allow all the forms to be used equally:

    FINDF=WIS=WHEREIS ff $*

(I am following a convention of writing the alias names in upper case
and the script in lower case.  This is only for ease in reading; ARUNZ
is not case sensitive.)  In fact, while I am at it, I usually throw in a
few other forms that someone might try and that are sufficiently
unambiguous that one can guess with some confidence that this is the
function the user intended:

    FIND.FILE=FILE.FIND=WIS=WHERE.IS ff $*

     Since (for ARUNZ version 0.9D and later) the characters after a
period are optional-match characters (they must match only if characters
are present), the first name will match FIND, FINDF, and FINDFILE (and
others).  The last form will match both WHERE and WHEREIS (and others).
Note that this single alias, which occupies 40 bytes in ALIAS.CMD
(including the CRLF), responds to 8 commonly used commands for finding
files on a system.  Thus the cost is a mere 5 bytes per command!!

     ZCPR33 introduced the ability to bypass path searching and go
straight to the extended command processor by prefixing a command with a
space or slash.  As users begin to avail themselves of this feature to
speed up command processing, it may happen that someone will enter the
command as "/FF" or " FF", thinking that "FF" is an alias for the real
command.  With the script above this will fail.  Therefore, I am now
recommending including the real command as an alias for itself to cover
this situation.  The final form for our file-finding alias (with an
extra change thrown in to allow the short form "WH") is thus:

    FIND.FILE=FILE.FIND=WIS=WH.EREIS=FF ff $*

     I have extended the use of command aliasing even to include the
results of common typing mistakes.  Richard Jacobson (Mr. Lillipute),
who calls my system quite often, either has a Wyse keyboard with very
bad bounce (as he claims) or is a lousy typist (and refuses to admit
it).  When he wants to display a directory, his command is more likely
to come out DDIR or DIRR than it is to come out correctly as DIR.  So I
added those two forms to my alias, so it now reads:

    XD.IR=DDIR=DIR.R dir $*

Is seven extra bytes too much to sacrifice for a friend!


Alternate Directory Changing References
---------------------------------------

     It is obviously very hard for users to remember the DU forms for
directories on a remote system, and that is why named directories are
provided.  But even names are not always easy to remember precisely.
Aliases can help by providing alternative names for logging into
directories, provided ZCPR33 has been assembled with the BADDUECP option
enabled so that invalid directory-change references are passed on to the
extended command processor.  My system has a directory called Z3SHELLS
(I think).  Since even I have trouble remembering that it is not Z3SHELL
or SHELLS or SHELL, I would have a line in ALIAS.CMD that reads:

    Z3SHELL:=SHELL:=SHELLS: z3shells:

     A further problem is that users often (and I occasionally) forget
to type the colon on the end.  It is very easy for ARUNZ to pick this up
as well and add the colon for you.  Just include the following alias:

    Z3SHELL=Z3SHELLS=SHELL=SHELLS z3shells:

All of these aliases can be combined into the single script:

    Z3SHELL.:=Z3SHELL.S:=SHELL.:=SHELL.S: z3shells:

All seven forms are covered by an entry of 49 bytes, a cost of 7 bytes
each.

     On my system I provide a complete set of aliases for all possible
directories so that any legal directory can be entered with or without
colons and using either the DIR of the DU form.  Thus, if Z3SHELLS is
B4, the script above would be:

    Z3SHELL.:=Z3SHELL.S:=SHELL.:=SHELL.S:=B4.: z3shells:

     Before ZCPR33 came along and provided this service itself, I would
allow callers to use the DU form to log into directories beyond the max-
drive/max-user limits by including aliases of the above form.  If the
maximum user area were 3 in the above example, the commands "B4:" and
"B4" would still have worked (even under ZCPR30) because ARUNZ mapped
them into a DIR form of reference.  Although this is no longer
necessary, a complete alias line like the one above covers all bases.
The user can even enter any of the commands with a leading space or
slash and they will still work.

     Finally, I usually provide a catch-all directory change alias to
pick up directory change commands that don't even come close to
something legal.  At the end of ALIAS.CMD (i.e., after all the other
directory-change aliases described above, so that they get first shot) I
include the line"

    ?:=??:=???:=????:=?????:=??????:=???????:=????????: echo
      d%>irectory %<$0%> is not an allowed directory.  %<t%>he^m^j
      valid directories are:;pwd

Thus when the user enters the command "BADDIR:", he get the PWD display
of the system's directories prefixed by the message

    Directory BADDIR: is not an allowed directory.  The
    valid directories are:

Note the use of Z33RCP's advanced ECHO command with case shifting ('%<
to switch to upper case and '%>' to switch to lower case) and control
character inclusion (caret followed by the character).


Abbreviated Commands
--------------------

     This category is closely releated to the first category described
above.  Consider transferring files.  One commonly enters a command like

    KMD SK FN.FT

Of course, some systems still use XMODEM, so it is handy to have an
alias (according to the first category above) that reads:

    XMODEM=KMD kmd $*

But why require the user to type KMD or XMODEM at all?  Why not allow
the option letters alone.  I provide the following set of aliases so
that users can invoke file transfer operations by entering the KMD
option letters alone as commands (along with other forms):

    S=SEND=DOWN.LOAD kmd s $1
    SK=SENDK=DOWNK kmd sk $1
    SP=SENDP=DOWNP kmd sp $1
    SPK=SENDPK=DOWNPK kmd spk $1
    SB=SENDB=BATCH=DOWNB kmd sb $*
    SBK=SENDBK=BATCHK=DOWNBK kmd sbk $*
    R=REC.EIVE=UP.LOAD kmd r $1
    RP kmd rp $1
    L=LIBSEND=SENDL=DOWNL kmd l $1 $2
    LK=LIBSENDK=SENDLK=DOWNLK kmd l $1 $2

Most of the longer alternative forms will never be used, but I decided
to be a 'big spender' and squander a hundred bytes!  Many of my users
(and I, myself) use the option letter alternatives -- with a leading
space or slash -- all the time.  I usually spruce up the aliases with
messages, so the SK alias might have a command script of:

    echo s%>ending file %<$1 (1k %>protocol);kmd sk $*

Even fancier scripts can be concocted.  One word of caution.  If you
allow the 'R' and 'SP' aliases, you cannot have the reset and space
commands in your RCP with the standard names.  I have them but have
changed the names to 'RES' and 'SPAC' respectively.


How to Implement ARUNZ
----------------------

     I would like to close with some tips on how to implement the scheme
described above.  Setting up ARUNZ as the extended command processor is
described in the ZCPR33 Users Guide and in the documentation with ARUNZ.
Basically, one renames ARUNZ.COM to CMDRUN.COM and places it in the root
directory (the last one listed in the symbolic path).  ARUNZ can be
configured to look for ALIAS.CMD either along the entire path, in the
root directory, or in a specifically designated directory.  I recommend
one of the latter two alternatives.

     The main trick I would like to call to everyone's attention is a
way to make ARUNZ perform at top speed as an extended command processor.
That is to arrange your disk so that the ARUNZ.COM and ALIAS.CMD files
are listed near the beginning of the disk directory and are stored near
the beginning of the disk data area.

     If you are starting with a fresh diskette (or hard disk), this is
easy.  Just copy these two files onto the disk first.  The question is,
what do you do if the disk already has files on it?  Here is what I do.
Run DU3 and go to group 0 (command 'G0'), where the directory starts.
Note which files are at the beginning of the directory, and note which
files have low group numbers allocated to them.

     To make things concrete, suppose we find two unimportant files
called NOTIMP1 and NOTIMP2 that meet these requirements and consume
enough allocation groups to accommodate ARUNZ.COM and ALIAS.COM.  First
we have to get these files out of the way.  We do this by copying them
to new names with commands like:

    PPIP NOTIMP1A=NOTIMP1;GO NOTIMP2A=NOTIMP2

(If they are in different user areas, then we include the user numbers
in the commands.)  Then we erase the original files to free up the
directory and disk space:

    ERA NOTIMP1;ERA NOTIMP2

Next we copy ARUNZ.COM and ALIAS.COM into their place.  Suppose, to deal
with the most complex case, that these files are already in the current
directory and that ARUNZ.COM is already called CMDRUN.COM.  We use the
following commands to move them into place:

    PPIP CMDRUN1.COM=CMDRUN.COM;GO ALIAS1.CMD=ALIAS.CMD
    REN CMDRUN.COM=CMDRUN1.COM;REN ALIAS.CMD=ALIAS1.CMD

With the rename commands, we answer 'Y' when prompted about deleting the
existing files.  Finally, we rename the two files that we moved out of
the way:

    REN NOTIMP1=NOTIMP1A;REN NOTIMP2=NOTIMP2A

If CMDRUN.COM and/or ALIAS.CMD had previously been stored in high group
numbers, you should now notice a very dramatic improvement in system
response (at least when you go to the ECP directly by entering commands
with a leading space or slash).  I get almost RAM-disk performance on my
system.