Using STDIN after exec() with ActiveState Perl

Yaribz has asked for the wisdom of the Perl Monks concerning the following question:

Hello, I have a problem when using exec() with ActiveState perl on Windows: it seems STDIN becomes multiplexed between the console and the perl program as soon as I call exec(). Here is a simple program to show what I mean:

use warnings;
use strict;

if(! $ENV{TEST}) {
  $ENV{TEST}=1;
  exec {$^X} ($^X,$0);
}

while(my $input=<STDIN>) {
  chomp($input);
  last unless($input);
  print "You typed: \"$input\"\n";
}

print "Exiting\n";
[download]

And here is the output when I just launch this program and try to enter "test1", "test2", "test3", "test4", "test5", and then the empty string to exit:

D:\test>perl test.pl

D:\test>test1
'test1' is not recognized as an internal or external command, operable
+ program or batch file.

D:\test>test2
You typed: "test2"
test3
'test3' is not recognized as an internal or external command, operable
+ program or batch file.
D:\test>test4
You typed: "test4"
test5
'test5' is not recognized as an internal or external command, operable
+ program or batch file.

D:\test>
Exiting
[download]

On the other hand, if I run this program on Linux it works perfectly:

~/test$ perl test.pl
test1
You typed: "test1"
test2
You typed: "test2"
test3
You typed: "test3"
test4
You typed: "test4"
test5
You typed: "test5"

Exiting
~/test$
[download]

Any idea about what is causing this? Is there any known workaround for this problem? Thanks.

Comment on Using STDIN after exec() with ActiveState Perl Select or Download Code

Replies are listed 'Best First'.
Re: Using STDIN after exec() with ActiveState Perl by LanX (Saint) on Jun 21, 2015 at 19:22 UTC
Simple.. Drop the exec. :) What's your intention anyway? Better just use pure Perl solutions instead if depending on OS features respectively their (incomplete) emulation. Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :) Je suis Charlie!}	[reply]
Re^2: Using STDIN after exec() with ActiveState Perl by Yaribz (Beadle) on Jun 21, 2015 at 19:38 UTC
I need the exec because I have to adjust the environment variables seen by perl at launch time (see programatically setting the LD_LIBRARY_PATH for the exact reason).	[reply]
Re^3: Using STDIN after exec() with ActiveState Perl by LanX (Saint) on Jun 21, 2015 at 19:52 UTC
Ehm... What's wrong with setting $ENV{PATH} in a BEGIN block? update Providing you are not allowed to set the correct environment in the registry. Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :) Je suis Charlie!}	[reply]
Re^4: Using STDIN after exec() with ActiveState Perl by Yaribz (Beadle) on Jun 21, 2015 at 20:00 UTC
Re^5: Using STDIN after exec() with ActiveState Perl by LanX (Saint) on Jun 21, 2015 at 20:19 UTC
Some notes below your chosen depth have not been shown here
Re^5: Using STDIN after exec() with ActiveState Perl by Anonymous Monk on Jun 21, 2015 at 20:13 UTC
Re^3: Using STDIN after exec() with ActiveState Perl by Anonymous Monk on Jun 21, 2015 at 19:39 UTC
windows doesn't have LD_LIBRARY_PATH	[reply]
Re^4: Using STDIN after exec() with ActiveState Perl by Yaribz (Beadle) on Jun 21, 2015 at 19:46 UTC
Re^5: Using STDIN after exec() with ActiveState Perl by Anonymous Monk on Jun 21, 2015 at 19:49 UTC
Some notes below your chosen depth have not been shown here
Re: Using STDIN after exec() with ActiveState Perl by Anonymous Monk on Jun 21, 2015 at 19:34 UTC
Any idea about what is causing this? Is there any known workaround for this problem? Thanks. Thats just how it works when you launch a process in the background on windows, which is what exec does. Windows doesn't have exec, its "semuliated" by perl Either way interactive <STDIN> is weak sauce Sure you could go messing with Win32::Console and you might figure stuff out , but I doubt it; a more definitive answer doesn't hold my interest	[reply]

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