NetNews Usenet Archive 1992 #30/NN_1992_30.iso/spool/comp/os/msdos/programm/11391

Text File | 1992-12-14 | 2.6 KB | 65 lines

Newsgroups: comp.os.msdos.programmer
From: [e-mail] (David Martin)
Path: sparky!uunet!pipex!demon!sound.demon.co.uk!dwm
Subject: Re: DOS CONSOLE OUTPUT
Reply-To: [e-mail]
Cc: [e-mail]
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Organization: Sound & Vision BBS (UK) 0932 252323
Lines: 51
Date: Sat, 12 Dec 1992 21:00:17 +0000
Message-ID: <[e-mail]>
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In article <[e-mail]> you write:
>    I am using fortran CALL FSYSTEM ('DOS COMMAND')
>to run various dos commands like MKDIR etc.  How do I get
>DOS to NOT write to the console during such operations, the
>console will be used for graphics application.
>
I started a thread 'Redirection to NUL from exec()' which you may have
seen, addressing the same problem from Turbo Pascal. I got lots of C
code and I was able to translate it quite easily into TP. I wish you
luck with Fortran, because I don't know a thing about it!

However, here is the pseudocode for the definitive solution:

1.  Open the device 'NUL' with whatever opens a file in Fortran.
2.  Get a copy of StdOut's filehandle with the dos service that does this,
    to a variable, eg. OrigStdOut. In C this is the dup() function. In TP
    I had to write my own. You can access it at the interrupt level by
    setting register AH to 45h, BX to the file handle you want a copy of
    (ie. 1=StdOut), and calling interrupt 21h. The copy of the (StdOut's)
    file handle is returned in AX.
3.  Call the dos service to duplicate a file handle, to equate NUL with
    StdOut, so the two move in unison. In C this is dup2(). In TP, again,
    I had to write my own... You set AH to 46h, BX and CX to the two
    handles of NUL and StdOut (1) respectively, and call 21h.
4.  Repeat 2 and 3 with StdErr (2) instead of StdOut.
5.  Close NUL.
6.  Do whatever, ie. CALL FSYSTEM ('DOS COMMAND')
7.  Execute step 3 again with BX = OrigStdOut and CX = StdOut then again
    with BX = OrigStdErr and CX = StdErr.
8.  Close OrigStdOut and OrigStdErr.

Reiterating, in a pseudo-language of my own invention:

1.  NulsHandle = open('nul')
2.  OrigStdOut = dup(1)
3.  dup2(NulsHandle,1)
4.  OrigStdErr = dup(2)
5.  dup2(NulsHandle,2)
6.  close(NulsHandle)
7.  call fsystem ('dos command')
8.  dup2(OrigStdOut,1)
9.  dup2(OrigStdErr,2)
10. close(OrigStdOut)
11. close(OrigStdErr)

I hope that that makes sense to you!

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