Perl script

[ajay458]

Hi,

I am trying to write a server client perl daemon that would do the following:

1) Server would send out requests to the clients to perform certain actions

2) Clients would receive the actions and send output back to server

TIA,
Ajay

 

[travs69]

Congratulations!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Travis - Those who say it cannot be done are usually interrupted by someone else doing it; Give the wrong symptoms, get the wrong solutions;

 

[ajay458]

Sincere apologies. I was very vague in my request. After looking at several examples on this forum, I have a sample script working with one-way communication but need help not only in sending data back to the server but to also convert these to daemons. BTW, here is my code:

Sender:

#!/usr/bin/perl

use IO::Socket::INET;

# Create a new socket
$MySocket=new IO::Socket::INET->new(PeerPort=>1234,Proto=>'udp',PeerAddr=>'3.24.141.91');

# Send actions
$def_action="Action: ";
print "\n",$def_action;
while($action=<STDIN>)
{
chomp $action;
if ($action ne '')
{
print "\n Action to be performed: '",$action,"'";
if($MySocket->send($action))
{
print ".....<done>","\n";
print $def_action;
}
}
else
{
# Send an empty action and exit
$MySocket->send('');
exit 1;
}
}


Receiver:

#!/usr/bin/perl
use IO::Socket::INET;

# Create a new socket
$MySocket=new IO::Socket::INET->new(LocalPort=>1234,Proto=>'udp');

$def_msg="\nReceived action.....\n";
print "\n",$def_msg;

while(1)
{
$MySocket->recv($action,128);
if ($action eq 'zonestats')
{
print "\nAction: $text\n";
print "Running ....\n\n";
$zonestats="/ztools/scripts/zonestat -l";
system($zonestats);
}
elsif ($action eq 'zonesize')
{
print "\nAction: $text\n";
print "Running zonesize....\n\n";
$zonesize="/ztools/scripts/zonesize -a";
system($zonesize);
}
# If action is empty, exit
else
{
print "No request made. Exiting\n";
exit 1;
}
}


Again, TIA.
Ajay

 

[Kirsle]

A few small things:

1) There's a way of using IO::Socket and IO::Select so that your server can create socket objects for each client that connects. With these sockets, you can send data back to the client, in a similar way that the client sends data to the server.

my $server_sock = IO::Socket::INET->new (LocalPort => ..., ...);
my $select = IO::Select->new($server_sock);

# infinite loop to accept new connections
# and respond to data
while (1) {
   my @ready = $select->can_read(); # get ready clients
   next unless @ready;

   foreach my $client_sock (@ready) {
      if ($client_sock == $server_sock) {
         # This is a new client connecting
         my $new_client = $server_sock->accept();
         $select->add($new_client);

         # Say hi to the client
         $new_client->send("Hello there!\n");
      }
      else {
         # This client was connected before, read their data
         my $buffer;
         $client_sock->recv($buffer,2048);

         # do whatever with $buffer

         # send a response
         $client_sock->send("My reply: $reply\n");
      }
   }
}

2) If you want to capture the output of a system command, don't use system(), use backticks.

my $tracert = `tracert google.com`;
print "Traceroute results: $tracert\n";

3) If you want to capture STDERR on your system commands in addition to STDOUT (since some utilities, usually in Unix, use STDERR a lot), redirect STDERR to STDOUT in your command.

my $tracert = `tracert google.com 2>&1`;

http://tldp.org/LDP/abs/html/io-redirection.html

more on I/O redirection.

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