4-May-86 13:51:39-PDT,3775;000000000001
Date: Sun, 4 May 86 15:49:25 cdt
From: Peter Wu <pwu@unix.macc.wisc.edu>
To: info-ibmpc-request@mosis
Subject: INPUT.C

INPUT - read a string from console in a batch file

SYNTAX

  INPUT <prompt> <var name>

Where <prompt> is a "quoted" string and <var name> is the name of
an environment variable to accept the input string.

Use \" to include the double quote character itself in the
prompt.

BRIEF DESCRIPTION

Just like BASIC's INPUT statement, except this one works in
batch files, so you can read a string from the user and use the
string in your batch file.

E.g. For kicks, you can put this in your autoexec.bat:

	echo off
	INPUT "Password:" pwd
	if %pwd%.==who. goto ok
	echo Access denied
	crash
	:ok
	echo.			    <- This prints an empty line
	echo Permission Granted

The string enterd will always be converted to lower case before
it is stored in the environment variable.

If the enviroment variable you specified already exist, it's
contend will be replaced by the user's input.

Since this programs stores the string in an environment variable,
you might run out of environment space. Here's a way to expand
your environment space to 992 bytes:

	shell=c:\command.com /p /e:62

Put the above line in your config.sys file.  This is an
undocumented feature.


WARNING

This program relies on several undocumented features of DOS 3.1.
It has been tested on PC AT and PC XT only.  For example, using
%pwd% to refer to the value of environment variable pwd might not
work in other DOS.  The INPUT program itself relies on
undocumented memory allocation block structure used by DOS to
find DOS's environment space.

I resort to undocumented features only because it's almost
impossible to accomplish all these by using documented features
alone.

If you try it on a clone and/or try it with a different version
of DOS, let me know whether or not it works.


EXAMPLES

There's this game called HACK that requires a configuration file
to indicate many options, among which the drive name of your ram
disk if you have one. I installed this game on a PC Network where
some PC's have ram disk and some don't. So this is what I put in
the HACK start up batch file:

	echo off
	copy F:\games\hack\hack33.cnf hack33.cnf
	INPUT "Drive name of your ram disk (if you have one)? " d
	if %d%.==. goto noram
	echo RAMDISK=%d% >> hack33.cnf
	:noram
	F:\games\hack\hack33
	       .
	       .

***

Here's a simple shell using INPUT:

	echo off
	:loop
	INPUT "% " cmd
	if %cmd%.==. goto loop
	if %cmd%.==exit. goto dos
	if %cmd%.==ls. goto ls
	%cmd%
	goto loop

	:ls
	dir/w
	goto loop

	:dos

This could be the cheapest way to con your friends into thinking
that you are running unix.

***

A user-friendly print command:

	echo off
	set fname=%1
	if not %1.==. goto doit
	:noarg
	INPUT "What file do you want to print? " fname
	if %fname%.==. goto noarg
	:doit
	copy %fname% lpt1

If the user call the batch file with a file name, then the file
will be printed, otherwise the user will be prompted for the name
of the file.

***

There are probably many other uses, but my imagination is quite
limited, if you found a good use for it, please let me know.


CREDIT

Michael Tsang of University of Wisconsin showed me how to locate DOS's
environment space.

Someone posted news to net.micro.pc mentioned the %name% undocumented
feature of DOS; this triggers me to write this program.


AUTHOR

Peter Wu
uucp: ..{ihnp4|seismo|harvard|topaz|allegra|ucbvax}!uwvax!uwmacc!pwu
arpa: uwmacc!pwu@uwvax.ARPA
USmail: 1309 Spring St. #206, Madison, WI 53715

Suggestions and comments are welcome.

[INPUT.C has been added to the Libary. -rag]