[25962] in Perl-Users-Digest
Perl-Users Digest, Issue: 8181 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Fri Jun 17 14:05:35 2005
Date: Fri, 17 Jun 2005 11:05:06 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Fri, 17 Jun 2005 Volume: 10 Number: 8181
Today's topics:
Re: Decorator pattern - IO::file <nobull@mail.com>
How to kill a forked child process... <moritz.karbach@desy.de>
Re: How to kill a forked child process... xhoster@gmail.com
Re: How to kill a forked child process... <nobull@mail.com>
Perl docs in CHM format? <slake2@ns.sympatico.ca>
Re: Perl docs in CHM format? <1usa@llenroc.ude.invalid>
Re: Perl docs in CHM format? <slake2@ns.sympatico.ca>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Fri, 17 Jun 2005 17:48:10 +0100
From: Brian McCauley <nobull@mail.com>
Subject: Re: Decorator pattern - IO::file
Message-Id: <d8uusb$53h$1@redhat2.bham.ac.uk>
bugbear wrote:
> Brian McCauley wrote:
>
>> bugbear wrote:
>>
>>> I would (greatly) like to be able to do something a LOT
>>> like pipes, without using (well...) pipes.
>>>
>>> I simple want to be able to build sequence
>>> of filters (at least if they were on Unix
>>> they would be called filters)
>>
>>> It appears that I can achive this by embodying
>>> my filter code in the read() method of IO::file
>>> (actually, IO;:handle withing IO::file).
>>
>> You could do that - but you'd be better off using tied filehandles (if
>> you need pre-5.8.x compatibility) or PerlIO layers otherwise.
>>
>
> Thanks for the pointer.
> As far as I (and google ...) can find,
> Perl layers appear to be a 'C' thing.
Yes but there is a module PerlIO::via to let you write them in Perl
using UPPERCASE methods rather as you do with tie()d things.
> Do you have any more help for me?
No much, I've never done this myself.
perldoc PerlIO::via
------------------------------
Date: Fri, 17 Jun 2005 18:26:09 +0200
From: Moritz Karbach <moritz.karbach@desy.de>
Subject: How to kill a forked child process...
Message-Id: <d8utj2$4tjhd$1@claire.desy.de>
...such that it doesn't become a zombie?
Hi,
I'm trying to implement something like this:
parent
|
|
|\ fork
| \
| \
| | child calls an system command,
| | exec("foo");
| |
fork /| |
/ | |
/ | |
watch- | | |
dog | | |
kills | | -
foo - |
|
|
But everytime the watchdog kills the child, the child becomes a zombie. Is
there a way to prevent this?
Here is some code (the run-function of my Command-class, which handles
system calls):
sub runFork # ()
{
my $this = shift;
my $fh_child; # pipe to the child process running the command
$pid = fork;
die "cannot fork: $!\n" unless defined($pid);
if ( $pid == 0 )
{
#
# child (command branch)
#
my @temp = ($EUID, $EGID);
my $orig_uid = $UID;
my $orig_gid = $GID;
$EUID = $UID;
$EGID = $GID;
# Drop privileges
$UID = $orig_uid;
$GID = $orig_gid;
# Make sure privs are really gone
($EUID, $EGID) = @temp;
die "Can't drop privileges"
unless $UID == $EUID && $GID eq $EGID;
open(STDERR, ">&STDOUT") or die "Can't dup STDOUT: $!";
$SIG{TTIN} = "IGNORE";
$SIG{TTOU} = "IGNORE";
$SIG{CHLD} = "IGNORE";
$SIG{CLD} = "IGNORE";
setpgrp(0,0);
exec($this->{command}) or die ("cannot run program: $!");
exit;
}
#
# fork once more for the watchdog for the timeout
#
my $wdog_id;
$wdog_id = fork;
die "cannot fork: $!\n" unless defined($wdog_id);
if ( $wdog_id == 0 )
{
#
# child - watchdog branch
#
$SIG{TTIN} = "IGNORE";
$SIG{TTOU} = "IGNORE";
$SIG{CHLD} = "IGNORE";
$SIG{CLD} = "IGNORE";
setpgrp(0,0);
sleep($this->{timeout});
kill(-9, $pid);
#`kill -9 $pid`;
exit;
}
#
# read output of the command
#
my @output = <$fh_child>;
close($fh_child);
$this->{output} = \@output;
#
# return value of the command
#
$this->{ret} = $?;
my $sig = $this->{ret} & 127;
#
# if command succeeded, we don't need the watchdog any more: kill!
#
if ( defined($wdog_id) && $sig != 9 )
{
kill(-9, $wdog_id);
}
return $this->{ret};
}
------------------------------
Date: 17 Jun 2005 16:38:52 GMT
From: xhoster@gmail.com
Subject: Re: How to kill a forked child process...
Message-Id: <20050617123852.847$k9@newsreader.com>
Moritz Karbach <moritz.karbach@desy.de> wrote:
>
> But everytime the watchdog kills the child, the child becomes a zombie.
> Is there a way to prevent this?
perldoc -q zombie
Xho
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------------------------------
Date: Fri, 17 Jun 2005 17:36:38 +0100
From: Brian McCauley <nobull@mail.com>
Subject: Re: How to kill a forked child process...
Message-Id: <d8uu6n$4sl$1@redhat2.bham.ac.uk>
Moritz Karbach wrote:
> ...such that it doesn't become a zombie?
>
> Hi,
>
> I'm trying to implement something like this:
>
> parent
> |
> |
> |\ fork
> | \
> | \
> | | child calls an system command,
> | | exec("foo");
> | |
> fork /| |
> / | |
> / | |
> watch- | | |
> dog | | |
> kills | | -
> foo - |
> |
> |
>
>
> But everytime the watchdog kills the child, the child becomes a zombie. Is
> there a way to prevent this?
The parent process of the child (not the sibling) must wait() or ignore
$SIG{CHLD}.
Have the parent fork off the watchdog process, then have the watchdog
fork-and-exec.
This doesn't really have anything to do with Perl, this is a Unix question.
------------------------------
Date: Fri, 17 Jun 2005 16:22:29 GMT
From: "Stephen Lake" <slake2@ns.sympatico.ca>
Subject: Perl docs in CHM format?
Message-Id: <9NCse.48454$Ph4.1275605@ursa-nb00s0.nbnet.nb.ca>
Can anyone tell me if the perl docs are available in Windows CHM Help file
format? I have looked with no success unless I was looking in the wrong
places.
If this question was asked already and answered then I appologize for
missing it.
Thanx
------------------------------
Date: Fri, 17 Jun 2005 16:34:12 GMT
From: "A. Sinan Unur" <1usa@llenroc.ude.invalid>
Subject: Re: Perl docs in CHM format?
Message-Id: <Xns96787FDD6DE9Easu1cornelledu@127.0.0.1>
"Stephen Lake" <slake2@ns.sympatico.ca> wrote in
news:9NCse.48454$Ph4.1275605@ursa-nb00s0.nbnet.nb.ca:
> Can anyone tell me if the perl docs are available in Windows CHM Help
> file format? I have looked with no success unless I was looking in the
> wrong places.
>
> If this question was asked already and answered then I appologize for
> missing it.
<URL:http://www.google.com/search?q=perldoc+chm+format>
<URL:http://htmlhelp.berlios.de/books/chm.php>
Sinan
--
A. Sinan Unur <1usa@llenroc.ude.invalid>
(reverse each component and remove .invalid for email address)
comp.lang.perl.misc guidelines on the WWW:
http://mail.augustmail.com/~tadmc/clpmisc/clpmisc_guidelines.html
------------------------------
Date: Fri, 17 Jun 2005 17:25:54 GMT
From: "Stephen Lake" <slake2@ns.sympatico.ca>
Subject: Re: Perl docs in CHM format?
Message-Id: <CIDse.48471$Ph4.1277376@ursa-nb00s0.nbnet.nb.ca>
For those interested I just found it in CHM here
http://htmlhelp.berlios.de/books/chm.php
haven't gone through it yet but there are a few files here for different
utilities and programs and languages (ie Python, g77, cpp, perl etc etc)
Just thought I would post this here in case others are interested in getting
it as well.
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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End of Perl-Users Digest V10 Issue 8181
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