'===========================================================================
' Subject: DOS COMMANDS IN ASIC PROGRAMS      Date: 01-11-96 (22:22)       
'  Author: John A. Kiernan                    Code: ASIC                   
'  Origin: kiernan@uwo.ca                   Packet: ASIC.ABC
'===========================================================================
rem   GETCOMSP.ASI  An ASIC (version 4 or 5) program that:
rem     (a) teaches the use of CALL for using internal DOS commands within
rem         an executable file. Much easier with ASIC than with QuickBasic!
rem         and it compiles to less than a tenth the size of a QB executable
rem         file.
rem     (b) shows how to make and write to a simple text file without
rem         having to bother with "OPEN" and "CLOSE"
rem   Read the last few lines of this file for compiling instructions.
rem   ===========
rem     Format 1 of ASIC's CALL command allows you to carry out internal
rem     and external DOS commands in a .COM or .EXE program made by ASIC.
rem     The syntax of Format 1 is  CALL (string1,string2)  where string1 is
rem     the full name of an executable program, and string2 contains its
rem     argument(s), including a leading space and any switches, etc.
rem  ============
rem     To run an internal DOS command (also, to run a batch file),
rem     string1 must be the current COMSPEC, found in the DOS "environment"
rem       You could change Env=30000 to Env=30 without offending anyone but
rem       the most eccentric batch file zealot! However, allowing for a huge
rem       environment does not enlarge or slow down the compiled program.
rem   ===========
       FOR Env = 1 TO 30000
           Env$=ENVIRON$(Env)
             Comsp=INSTR(Env$,"COMSPEC")
               IF Comsp > 0 THEN
                 Comspec$=Env$
                 GOTO GotIt:
               ENDIF
       NEXT Env
                rem  The program cannot get this far (unless you have been
                rem  silly and have removed the COMSPEC statement from the
                rem  environment.
       PRINT "Couldn't find COMSPEC - This should be utterly impossible."
       GOTO Finished:
rem                     The next lines extract the COMSPEC
rem                     (after the = sign) and display it.
   GotIt:
       Length=LEN(Comspec$)
       EqualsPos=INSTR(Comspec$,"=")
       ComspLength=Length-EqualsPos
       Comspec$=RIGHT$(Comspec$,ComspLength)
       PRINT Comspec$
rem                     Pause the screen display
       PRINT "Press any key to continue . . ."
   Wait:
       Key$=INKEY$
         IF Key$="" THEN Wait:
rem                            Comspec$ shows which command processor you
rem                            are using. This may not be C:\COMMAND.COM.
rem                            See NOTES_AT_END:
rem   * ASIC's  CALL  is used to invoke DOS internal commands.      *
rem   * Spaces around /C matter a lot!  You can't add the " /C" to  *
rem   * the  Comspec$  variable.   The  /C  (with space before and  *
rem   * after) MUST be in the second part (string2) of the argument *
rem   * that follows CALL.  See also NOTES_AT_END:                  *
         CALL (Comspec$," /C dir/w")
         CALL (Comspec$," /C ver")
         CALL (Comspec$," /C path")
rem   ===========
rem  The argument following the /C  can be quite complicated,
rem  BUT IT CANNOT BE VERY LONG - an annoyance, mentioned in the
rem  commented code that follows.
 CALL (Comspec$," /C echo 12345678901234567890123456789012345678901234567890")
 PRINT " Only the first 24 of these numerals are displayed on the screen."
rem   ===========
rem  Redirection & piping are OK.  The next line makes a text
rem  file called JUNK in the default directory.
        CALL (Comspec$," /C echo This file is Junk! >JUNK")
rem        The above example illustrates the limitation of the
rem        length of string2 in ASIC's CALL command.  If you add
rem        one space anywhere in the string (for example, after
rem        "echo" or after ">" the string is truncated and makes
rem        a file named JUN instead of JUNK.
rem            You cannot get round this length limitation by using a
rem        variable for string2.
rem   ===========
rem  To append things to a file, use the DOS convention of
rem  two greater-than signs.
       CALL (Comspec$," /C echo Second line >>JUNK")
       CALL (Comspec$," /C ver >> JUNK")
       CALL (Comspec$," /C echo. >>JUNK")
       CALL (Comspec$," /C set >> junk")
       CALL (Comspec$," /C echo. >>JUNK")
       PRINT "  Now enter TYPE JUNK at the DOS prompt, to read the"
       PRINT "  redirected and appended outputs of internal DOS commands"
       PRINT "  executed within GETCOMSP.COM"
       PRINT "                                 You can then delete JUNK."
       PRINT ""
rem   ===========
rem   With this tiny program you have made a file and added text to it
rem   without having to bother with the "OPEN" and "CLOSE" commands of
rem   ASIC and other BASIC languages. Once you get the hang of the ASIC's
rem   CALL command, it's nearly as easy as writing a batch file.
rem   ===========
   Finished:
       END
   NOTES_AT_END:
rem  Command processors.
rem     Wise users of computers know that 4DOS.COM is better in every way
rem     than the COMMAND.COM that comes with MS-DOS. 4DOS is not the only
rem     command processor that's better than COMMAND.COM - there's DR DOS
rem     and NDOS and probably others too.
rem  Punctuation of the CALL command.
rem     If the punctuation of the CALL (string1,string2) command is wrong,
rem     the compiled ASIC program (a) doesn't work, and (b) uses up
rem     oodles of memory in temporary command processors - about 60kB each
rem     time you run it. Recover the eaten memory by entering EXIT several
rem     times at the DOS prompt. The DOS 6.0 command MEM/c/p will show how
rem     much memory is being used or wasted.
rem  How to compile this program.
rem     If this file, named GETCOMSP.ASI is in the same directory
rem     as the ASIC program files, the command:
rem                                             ASICC GETCOMSP
rem     will make GETCOMSP.COM (2659 bytes).
rem   ===========
rem     Written and put in the public domain by John A. Kiernan, Jan.1996
rem                                             (kiernan@uwo.ca)