Passing Args via Exec (2)

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

Hi,
This is a continuation of the my origional thread -
Passing Args via Exec
I'm trying to pass arguments to child script using the following code -

#!/usr/bin/perl -w

use strict;

$|++;

$ENV{PATH} = "/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/
+sbin";

use CGI qw(:all delete_all escapeHTML);

print header(),
start_html(-title => "Traceroute Results");
print h1("Traceroute Results");

#open STDERR, ">&=1";

exec '/usr/bin/perl', '-T', 'child.pl', 'number=4' or die "Cannot exec
+ute : $!";

print end_html;
[download]

I call this on the command line with - "perl new3.cgi" and I get -

Content-Type: text/html; charset=ISO-8859-1

<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE html
        PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US" xml:lang="en-U
+S"><head><title>Traceroute Results</title>
</head><body><h1>Traceroute Results</h1>param: 4
Command line reporter
Called with 1
parameters which was
1: number=4
*
*
[download]

I then call this with my browser and get -

Traceroute Results
param: Command line reporter Called with 1 parameters which was 1: num
ber=4 * *
[download]

Notice "Param:" , theres no number passed but if I uncomment the line - open STDERR, ">&=1"; I get -

Traceroute Results
Use of uninitialized value in concatenation (.) or string at child.pl 
+line 10. param: Command line reporter Called with 1 parameters which 
+was 1: number=4 * *
[download]

The command line call is working fine, the browser calls are not So I'm guessing my problem has something to do with buffering. THe actual parent script I wish to call is a rework of the following -
http://www.stonehenge.com/merlyn/LinuxMag/col39.html
and is as follows -


#!/usr/bin/perl -w

use strict;

$|++;
 
 $ENV{PATH} = "/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local
+/sbin";
 
 use CGI qw(:all delete_all escapeHTML);
 
 sub show_form {
 print header, start_html("Traceroute"), h1("Traceroute");
 print start_form;
 print submit('traceroute to this host:'), " ", textfield('host');
 print end_form, end_html;
 }
 
 sub get_cache_handle {
 require Cache::FileCache;
 
 Cache::FileCache->new
 ({
 namespace => 'tracerouter',
 username => 'nobody',
 default_expires_in => '30 minutes',
 auto_purge_interval => '4 hours',
 });
 }
 
 sub get_session_id {
 require Digest::MD5;
 
 Digest::MD5::md5_hex(Digest::MD5::md5_hex(time().{}.rand().$$));
 } 



 if (my $session = param('session')) { # returning to pick up session 
+data
 my $cache = get_cache_handle();
 my $data = $cache->get($session);
 unless ($data and ref $data eq "ARRAY") { # something is wrong
 show_form();
 exit 0;
 }


 print header(),
 start_html(-title => "Traceroute Results",
  ($data->[0] ? () :
  (-head => ["<meta http-equiv=refresh content=5>"])));
 print h1("Traceroute Results");
 print pre(escapeHTML($data->[1]));
 print p(i("... continuing ...")) unless $data->[0];
 print end_html;
 } elsif (my $host = param('host')) { # returning to select host
 if ($host =~ /^([a-zA-Z0-9.\-]{1,100})\z/) { # create a session
 $host = $1;  # untainted now
 my $session = get_session_id();
 my $cache = get_cache_handle();
 $cache->set($session, [0, ""]); # no data yet
 
 if (my $pid = fork) { # parent does
 delete_all(); # clear parameters
 param('session', $session);
 print redirect(self_url());
 } elsif (defined $pid) { # child does
 close STDOUT; # so parent can go on
 unless (open F, "-|") {
 open STDERR, ">&=1";

exec '/usr/bin/perl', '-T', 'child.pl', 'number=4' or
 die "Cannot execute : $!";


 }
 my $buf = "";
 while (<F>) {
 $buf .= $_;
 $cache->set($session, [0, $buf]);
 }
 $cache->set($session, [1, $buf]);
 exit 0;
 } else {
 die "Cannot fork: $!";
 }
 } else {
 show_form();
 }
 } else {  # display form
 show_form();
 }
 
 exit 0;
[download]

20040828 Janitored by Corion - localized link

Comment on Passing Args via Exec (2) Select or Download Code

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Re: Passing Args via Exec (2) by Anonymous Monk on Aug 28, 2004 at 22:49 UTC
This works - `#!/usr/bin/perl -w use strict; $\|++; use CGI; my $cgi = CGI->new; $ARGV[0] =~ /number=(\d+)/; $number = $1; for(my $i=0;$i<$number;$i++) { print("*\n"); sleep 1; }` [download]	[reply] [d/l]