Re^15: Using STDIN after exec() with ActiveState Perl

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Re^16: Using STDIN after exec() with ActiveState Perl by Yaribz (Beadle) on Jun 21, 2015 at 22:04 UTC
Here is the code for test.pl: `use warnings; use strict; use Module::Load; if(! $ENV{SPRING_WRITEDIR}) { $ENV{SPRING_WRITEDIR}='E:\\test'; exec {$^X} ($^X,$0); } $ENV{PATH}="E:\\springrts;$ENV{PATH}"; load("PerlUnitSync"); PerlUnitSync::Init(0,0); my $writeDir=PerlUnitSync::GetWritableDataDirectory(); print "writeDir=$writeDir\n";` [download] Here is the output: `E:\test>perl test.pl E:\test>writeDir=E:\test\` [download] And now the output if I comment the exec line: `E:\test>perl test.pl writeDir=D:\Documents\My Games\Spring\` [download] As you can see the SPRING_WRITEDIR environment variable is not taken into account if I don't use exec.	[reply] [d/l] [select]
Re^17: Using STDIN after exec() with ActiveState Perl by RonW (Parson) on Jun 22, 2015 at 20:30 UTC
Update: Ok, so can't use a BEGIN block... On Windows, `exec` is simulated in a strange way. Apparently, it's creating a new process and exiting the caller before the new process exits. (Update 2: On Linux, `exec` does not start a new process, it loads a new executable into the calling process. From the command shell's point of view, the process it launched is still running, so it's not trying to read STDIN.) Your problem with `system` is that you need to `exit` after `system` returns: `use warnings; use strict; use Module::Load; if(! $ENV{SPRING_WRITEDIR}) { $ENV{SPRING_WRITEDIR}='E:\\test'; system {$^X} ($^X,$0); exit; }` [download] Yes, you will have 2 Perl processes where you had 1, but one of those will be idle while waiting on the other to exit. Please try: `use warnings; use strict; BEGIN { $ENV{SPRING_WRITEDIR}='E:\\test'; $ENV{PATH}="E:\\springrts;$ENV{PATH}"; } use Module::Load; load("PerlUnitSync"); PerlUnitSync::Init(0,0); my $writeDir=PerlUnitSync::GetWritableDataDirectory(); print "writeDir=$writeDir\n";` [download] This will set the environment before Module::Load is loaded.	[reply] [d/l] [select]
Re^18: Using STDIN after exec() with ActiveState Perl by Yaribz (Beadle) on Jun 23, 2015 at 08:59 UTC
Thanks for looking into this. The problem is that my script must be able to modify the environment variables as many times as needed during its execution, which would lead to a growing number of idle perl processes with this solution.	[reply]
Re^19: Using STDIN after exec() with ActiveState Perl by Anonymous Monk on Jun 23, 2015 at 09:21 UTC
Re^20: Using STDIN after exec() with ActiveState Perl by Yaribz (Beadle) on Jun 23, 2015 at 09:35 UTC
Re^19: Using STDIN after exec() with ActiveState Perl by RonW (Parson) on Jun 23, 2015 at 17:37 UTC
Re^20: Using STDIN after exec() with ActiveState Perl by Yaribz (Beadle) on Jun 23, 2015 at 20:04 UTC
Re^17: Using STDIN after exec() with ActiveState Perl by Anonymous Monk on Jun 21, 2015 at 22:10 UTC
What does your `perl -V` return? I suspect either some old bug in some old version of perl, ... or some bug in SWIG LD_LIBRARY_PATH is pretty much the only variable that is special enough to demand exec ( Should I set LD_LIBRARY_PATH?, Why LD_LIBRARY_PATH is bad )	[reply] [d/l]
Re^18: Using STDIN after exec() with ActiveState Perl by Yaribz (Beadle) on Jun 21, 2015 at 22:19 UTC
output of perl -V: http://pastebin.com/6bE8L9vA	[reply]
Re^19: Using STDIN after exec() with ActiveState Perl by Anonymous Monk on Jun 21, 2015 at 23:03 UTC
Re^20: Using STDIN after exec() with ActiveState Perl by Yaribz (Beadle) on Jun 23, 2015 at 09:31 UTC
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Re^20: Using STDIN after exec() with ActiveState Perl by Yaribz (Beadle) on Jun 21, 2015 at 23:19 UTC