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Re: using wshell.exec causes lockup while reading the output - what to do ?

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On Wed, 17 Jun 2020 18:51:41 +0200, R.Wieser wrote:
> 
> That should not be a problem.  As long as the program that is exec-ed runs 
> it should be generating output (in a seperate thread I presume), and the 
> buffer should eventually gain some new contents.   But no, I can see the 
> output stops somewhere rather early, nowhere near to the end.

It doesn't matter whether the program output/error is written by multithread
or not, because the problem lies within the TextStream object's methods.

> Regardless, do you have any suggestions to how to solve it/what to try ? 

When the input is a character device, instead of a file, don't use counted
read operation unless you know exactly when the program stops writing data
into a standard handle. That would produce a deadlock unless the program
generate at least the same length of data being requested to read.

In your code, you have these lines:

if not oExec.stdout.atendofstream then wscript.echo oExec.stdout.read(1000)
if not oExec.stderr.atendofstream then wscript.echo oExec.stderr.read(1000)

If the program writes some lines totalling 500 bytes into standard output,
the script will be stuck within `oExec.stdout.read(1000)` because it's
expecting 500 more bytes of data.

It'be better to read the program output line by line like below.

  do while not oExec.stdout.atendofstream
    wscript.echo oExec.stdout.readline
  loop

> Or should I conclude that trying to grab output from an "exec" method is 
> undependable, and thus simply a waste of time ?

What's wrong with that? I use it myself to parse various programs' output,
as well as input commands into the executed programs.

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Thread

using wshell.exec causes lockup while reading the output - what to do ? "R.Wieser" <address@not.available> - 2020-06-17 14:32 +0200
  Re: using wshell.exec causes lockup while reading the output - what to do ? "Mayayana" <mayayana@invalid.nospam> - 2020-06-17 08:48 -0400
  Re: using wshell.exec causes lockup while reading the output - what to do ? JJ <jj4public@vfemail.net> - 2020-06-17 22:12 +0700
    Re: using wshell.exec causes lockup while reading the output - what to do ? "R.Wieser" <address@not.available> - 2020-06-17 18:51 +0200
      Re: using wshell.exec causes lockup while reading the output - what to do ? JJ <jj4public@vfemail.net> - 2020-06-18 19:42 +0700
        Re: using wshell.exec causes lockup while reading the output - what to do ? "R.Wieser" <address@not.available> - 2020-06-18 17:26 +0200
          Re: using wshell.exec causes lockup while reading the output - what to do ? JJ <jj4public@vfemail.net> - 2020-06-19 21:16 +0700
            Re: using wshell.exec causes lockup while reading the output - what to do ? "R.Wieser" <address@not.available> - 2020-06-19 19:08 +0200
              Re: using wshell.exec causes lockup while reading the output - what to do ? JJ <jj4public@vfemail.net> - 2020-06-20 22:40 +0700
                Re: using wshell.exec causes lockup while reading the output - what to do ? "R.Wieser" <address@not.available> - 2020-06-20 18:56 +0200
                Re: using wshell.exec causes lockup while reading the output - what to do ? JJ <jj4public@vfemail.net> - 2020-06-21 12:33 +0700
                Re: using wshell.exec causes lockup while reading the output - what to do ? "R.Wieser" <address@not.available> - 2020-06-21 08:53 +0200
                Re: using wshell.exec causes lockup while reading the output - what to do ? JJ <jj4public@vfemail.net> - 2020-06-21 20:58 +0700
                Re: using wshell.exec causes lockup while reading the output - what to do ? "R.Wieser" <address@not.available> - 2020-06-21 17:46 +0200

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