From:	SMTP%"RELAY-INFO-VAX@CRVAX.SRI.COM"  7-JUL-1994 14:31:19.52
To:	EVERHART
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Subj:	Re: can you make a SETDEFAULT program in VAX-C?

Date: Thu, 07 Jul 1994 11:52:35 +0100
From: Arne Vajhoej <ARNE@kopc.hhs.dk>
Subject: Re: can you make a SETDEFAULT program in VAX-C?
To: york@NEPTUNE.ECE.SYR.EDU, INFO-VAX@SRI.COM
Message-id: <01HEF9I5UP7696VKUZ@kopc.hhs.dk>
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>         I have seen many excellant "SET DEFAULT" programs (in DCL,MACRO,
> FORTRAN, and PASCAL).  But I would like to find (or write) one in VAX-C.
> 
>         Can this be done?

Ofcourse it can !

>         In PROGRAMING IN VAX-C manual, it says:
>                 "For CHDIR() to be effective accrossed images, it
>                  should be executed in SUPERVISOR, KERNAL, or
>                  EXECUTIVE mode."
> 
>         OK, so how do I change modes?

Via the system-services SYS$CMEXEC or SYS$CMKRNL, but it is in general not
safe to call C RTL routines from other than user mode (but many many of them
will actual work).

It is much better to use the same routines (SYS$SETDDIR and LIB$SET_LOGICAL)
that the programs written in other languages.

>         Also, I did not see any calls to modify the PROMPT,

For a unpriviliged program then terminate the program with a LIB$DO_COMMAND
that sets the prompt.

>                                                              nor to create
> GLOBAL SYMBOLs (for PUSHDIR/POPDIR functions).

The routines LIB$SET_SYMBOL and LIB$GET_SYMBOL can be used for global
symbols too.

PS: You will see much of this demonstrated in a small utility available
    via anonymous FTP from KOPC.HHS.DK - see description attached below.
    (but it is FORTRAN not C)

                                                          Arne

Arne Vajhøj                             local DECNET:  KO::ARNE
Computer Department                     PSI:           PSI%238310013040::ARNE
Business School of Southern Denmark     Internet:      ARNE@KO.HHS.DK

================================================================================

  [.SETPMT]SETPMT.ZIP
    Description : changes the prompt to current directory whenever
                  current directory is changed via DCL (and that is
                  always the case unless some programs calls SYS$SETDDIR
                  themselves). No privs required.
    Source      : FORTRAN
    Binary      : OBJ's and EXE's in SETPMT_BIN.ZIP (compiled with
                  FORTRAN 6.1 and linked on VMS 5.5-2)
    Notes       : needs VERB or VMS 5.5
                  (VAX only)
    Posted      : not