Running a perl script in background

I am designing a web interface to generate some reports.
The perl script that generates these reports takes about 15 minutes to run.
I donot want the user to wait that long so I am trying to run it as a background.
This is what I have implemented-


if (!defined($pid=fork)) {
die "Unable to fork!";
}
elsif (! $pid){
#child
`/home/scripts/uptime_pgm /home/scripts/addresses/all_NetworkIP`; #script to be run
}
else {
#parent
     
print<<END_of_Start;
Content-type: text/html

<HTML>
   <HEAD>
   <TITLE>Report Generator</TITLE>
   </HEAD>
   
   <BODY>
   <P>Processing your request View the results page after 15 minutes</P>
   </BODY>
</HTML>
END_of_Start
exit;
     
}

The problem is the browser doesnot close, it closes only after the child has finished.
Why is this code not working?
manadAsked:
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Weiping DuSenior Web DeveloperCommented:
Not sure this will work, how about use child process to print out HTML msg and use parent process to generate report. such as:
if($myspid = fork())
{
    Print_HTML_Msg();
    exit(0);
}
`/home/scripts/uptime_pgm /home/scripts/addresses/all_NetworkIP'
0
bobbissonCommented:
from perlform manpage (perl 5.6.1):

--
exit() always exits just the executing pseudo-process, after automatically wait()-ing for any outstanding child pseudo-processes.  Note that this means that the process as a whole will not exit unless all running pseudo-processes have exited.

A way to mark a pseudo-processes as running detached from their parent (so that the parent would not have to wait() for them if it doesn't want to) will be provided in future.
--

Possible solution that comes to my mind is to create a daemon process that will run your script on a special signal, like this:


--
daemon.pl

#!/perl

use POSIX qw(setsid);
use POSIX qw(:signal_h);

sub _sig_HUP {
# do necessary handling
}

open(FILE,'>/path/to/lock') or die "Can't create lock file: $!\n";
print FILE $$;
close FILE;


chdir '/'                 || die "Can't chdir to /: $!\n";

open STDIN,  '/dev/null'  || die "Can't read /dev/null: $!\n";
open STDOUT, '>/dev/null' || die "Can't write to /dev/null: $!\n";

defined(my $pid = fork)   || die "Can't fork: $!\n";
exit 0 if $pid;

setsid || fatal $self("Can't start a new session: $!");

$SIG{HUP}  = sub { &_sig_HUP };

sleep

--

--
script.pl

#!/perl

use POSIX qw(:signal_h);

open FILE,'/path/to/lock';
my $daemon = <FILE>;
close FILE;
# get daemon pid somehow
kill SIGHUP,$daemon;

# print HTML
--
0

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jmcgOwnerCommented:
Nothing has happened on this question in over 7 months. It's time for cleanup!

My recommendation, which I will post in the Cleanup topic area, is to
accept answer by bobbisson.

Please post any comments here within the next seven days.

PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!

jmcg
EE Cleanup Volunteer
0
bobbissonCommented:
I agree :)
0
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