From:	MERC::"uunet!CRVAX.SRI.COM!RELAY-INFO-VAX" 28-MAY-1992 08:09:21.26
To:	info-vax@kl.sri.com
CC:	
Subj:	Re: SUMMARY: Case of the commandline-how do I get it?

A late entry here....

  A third command-line-grabbing technique which I haven't seen mentioned,
is possible if you're programming in C.  The argc and argv arguments to 
the main() function pick up command-line elements in a way slightly 
different from EITHER the "foreign" OR "native" command-verb-definition
mechanisms.

  Specifically, where the "native" (.CLD, CLI$xxxx...) command mechanism
forces all command-line input to UPPERCASE, the C RTL argc/argv forces 
everything to LOWERCASE.  BOTH mechanisms will "preserve" the typed-in
case of anything on the command line that was enclosed in double quotes 
("), but the native-command mechanism will hand your application a string
that INCLUDES the surrounding quotes -- forcing the application to strip/
parse these -- whereas the C RTL will NOT.

  If you're NOT programming in C, you might still be able to use the  
C RTL's facility for retrieving command-line information.  I program in
VAX MACRO assembly language, and tend to debug even high-level-language
code at the instruction level, and have thus observed that VAX C obtains
its arguments by a two-instruction sequence:

      moval -8(sp),sp			; Reserve eight bytes' dynamic storage
      jsb   g^C$MAIN_ARGS  		; Obtain command-line arguments

After this sequence, the program's top-level argument stack has been
changed to a three-entry argument list: argument 1 is C's "argc", by
value; argument 2 is C's "argv", by reference (argument 2 is the address
of a list of longwords, which in turn are pointers to argv[0], argv[1],
etc. as null-terminated ASCII strings); argument 3 is another pointer,
to an array identical in structure to the argv[] array but containing 
the primordial C "environment" strings, e.g. "HOME=...", "PATH=...", 
etc. etc...

  I don't know if this helps anyone, but I use it (though not in produc-
tion code).

  Chris Chiesa
    Chris_F_Chiesa@cup.portal.com