in reply to Re^2: Asynchronous Processing a command execution
in thread Asynchronous Processing a command execution

Please show some effort on your part by reducing the problems to the absolute minimum of code. In your case, the problem is that your child process running the ssh command does not produce output. This is because you wrongly transcribed merlyn's code:

# Original code:
        =42=          my $buf = "";
        =43=          while (<F>) {
        =44=            $buf .= $_;
        =45=            $cache->set($session, [0, $buf]);
        =46=          }
        =47=          $cache->set($session, [1, $buf]);
        =48=          exit 0;

[download]

Your code does not read from the STDOUT of the SSH process. In fact, I don't think you understood how Net::SSH works at all. I think it directly returns the output of the command after the command has run, so using Net::SSH won't help you, at least in the way you've used it here:

                        $cmd="ls -l";
                        my($stdout, $stderr, $exit) = $ssh->cmd($cmd);
                        my $buf = "";
                        while ($stdout) 
                                {
                                        $buf .= $_;
                                        $cache->set($session, [0, $buf
+]);
                                }
                        $cache->set($session, [1, $buf]);

[download]

Please review your code and the documentation for Net::SSH and consider how they can be used for your program.

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Re^4: Asynchronous Processing a command execution
by Alfaromeo (Initiate) on Jul 04, 2008 at 08:49 UTC
    Corion , Please check the below code.I have slightly modified the code by excluding SSH and putting in the old code in itself.But this page is called from another HTML. If this works , I will modify the section in fork for SSH.Right now it shows premature end of script headers error. 
    !/usr/bin/perl
use strict;
$l++;
use CGI qw(:all);       # import shortcuts
use Fcntl qw(:flock);   # imports LOCK_EX, LOCK_SH, LOCK_NB
use CGI::Carp qw(warningsToBrowser fatalsToBrowser); # For Debugging
use Net::SSH::Perl;
use CGI qw(:all delete_all escapeHTML);
use Net::SSH::Perl::Constants qw( :msg );

my ($TITLE,$DeploySvr,$KIT,$ssh,$UNM,$Pass,$stdout,$stderr,$exit,$cmd,
+$session,$cache,$data,$pid,$packet,);

    if (my $session = param('session'))
        { # returning to pick up session data
            $cache = get_cache_handle();
            $data = $cache->get($session);
            unless ($data and ref $data eq "ARRAY") 
            { # something is wrong
                 exit 0;
            }
            print header;        
              print start_html(-title => "Logging...",($data->[0] ? ()
+ : (-head => ["<meta http-equiv=refresh content=5>"])));
            print h1("Logging...");
            print pre(escapeHTML($data->[1]));
            print p(i("... continuing ...")) unless $data->[0];
            print end_html;
        } 
    else 
        {
            $session = get_session_id();
            $cache = get_cache_handle();
            $cache->set($session, [0, ""]); # no data yet
            $DeploySvr=param('DrpServer');
            $KIT=param('TxtKit');
            $UNM=param('username');
            $Pass=param('password');
                if ($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 o
+n
                        $DeploySvr="113.128.122.27";
                        unless (open F, "-|")
                            {
                                open STDERR, ">&=1";
                                exec "/usr/sbin/traceroute", $DeploySv
+r;
                                die "Cannot execute traceroute: $!";
                            }
                        my $buf = "";
                        while (<F>) 
                            {
                                $buf .= $_;
                                $cache->set($session, [0, $buf]);
                            }
                        $cache->set($session, [1, $buf]);
                        
                    } 
                else
                    {
                        die "Cannot fork: $!";
                    }
        }

sub get_cache_handle
{
  require Cache::FileCache;
  Cache::FileCache->new
  ({
        namespace => 'LogOutput',
        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().$$));
}

    [download]
[reply]
[d/l]

      You don't show any effort in fixing your errors. See the webserver error log for why your program does not run at all. This is a basic CGI debugging problem and has little if nothing to do with SSH at all.

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