Hi Monks,

I have a problem with Net::Telnet module. I use it to login to a device via TCP/IP and get some information from the device. Depending on the connection the prompt at the device side is IP1x with x between 0-7.

The problem is that on sending a command the script behaves inconsistent. Sometimes I direclty receive the replied message from the device and sometimes I have to give another enter to receive the message.

I am still in test-mode, but would like to automate the script and am not sure how to deal with the above. Attached is the script and the debug output of the telnet module. The difference between bouth debug outputs is that in the second case the enter command is there > 0x00000: 0a                                                  .

What am I doing wrong that causes this inconsistent behaviour? 

#!/usr/bin/perl -w
#
#   test
#   ------
#   Test connection to equipment via TCP/IP

use vars qw( $VERSION );
use Getopt::Long;
use File::Basename;
use Net::Telnet;
use strict;
use warnings;

local $|=1;

$VERSION = 20110214;


# Process options and input arguments

Getopt::Long::Configure( "prefix_pattern=(-|\/)" );

my %Config;
my $Result = GetOptions( \%Config,
        qw(
            ip|i=s
            port|p=s
            help|?|h
          ) );
$Config{help} = 1 if( ! $Result );

if ( $Config{help} || not exists($Config{ip}) )
{
    Syntax();
    exit();
}


my $hostname;
my $hostport;

$hostname=$Config{ip};
$hostport=$Config{port};

# Connect to receiver

my $file1="debug.out";
my $file2="input.out";

my $Rtelnet = new Net::Telnet ( Timeout=>1, Errmode=>'die', Prompt => 
+'/\>/', Binmode=>1,Dump_log=>$file1,Input_log=>$file2,Telnetmode=>0);
+ 
$Rtelnet->open(host => $hostname, port => $hostport); 

# Stop previous output and clear buffers
$Rtelnet->put("SSSSSSSSSS\n");
$Rtelnet->buffer_empty;

# Send an empty line WHY??-otheriwse it does not work...
$Rtelnet->cmd('');

# find out the name of the port (format IP##)
my $prompt;
my $tryout=0;
my $Rdevice;
while ( $tryout <= 5 ) {
    my @lines2=$Rtelnet->cmd('');
    $prompt=pop(@lines2);
    if (!(defined($prompt))) {
        print "Read on IP port timed out while testing for prompt\n";
    } elsif ( $prompt =~ /(\S\S\d\d)/i ) {
        $Rdevice=$1;
        last;
    }
    $tryout++;
}
if ( $tryout > 5 ){
    die "Unable to determine the prompt";  
} 
$prompt=$Rdevice.">";
my $Rreprompt='/'.$prompt.'$/i';
print "Prompt is [$prompt]\n" ;

# Set prompt as match operators (for record seperators) 

$Rtelnet->prompt($Rreprompt);

# Start command line mode

print "Connected to $hostname in command mode; enter command, quit or 
+exit\n";

print $prompt;

my $data;
while (<STDIN>) {
    chomp;
    last if (/^quit$/i || /^exit$/i); 
    $data=Rcmd($_);
    print "$data";
    print $prompt;
} 


# End of command mode

sub Rcmd{

    my ($cmd)=@_;
    my $buffer;
    my @lines;
    @lines = $Rtelnet->cmd(String=>$cmd);

    $buffer=join('',@lines);

    return $buffer;
}

sub Syntax{

    my( $Script ) = ( $0 =~ m#([^\\/]+).pl$# );
    my $Line = "-" x length( $Script );
    print << "EOT";
$Script                                            (Version: $VERSION)
$Line
Download, mirror and remove internal data files.

Syntax: 
  $Script -i <Hostname> [-p <Port> -h]

  -i <Hostname>...IP name/address.
  -p <Port>.......IP port to conect to.                  
  -?|h|help.......This help.

Examples:
  $Script -i 192.168.0.1 -p 8888

EOT

}

[download]
Output with direct response 
> 0x00000: 53 53 53 53  53 53 53 53  53 53 0a                  SSSSSSS
+SSS.

> 0x00000: 0a                                                  .

< 0x00000: 49 50 31 32  3e                                     IP12>

> 0x00000: 0a                                                  .

< 0x00000: 49 50 31 32  3e                                     IP12>

> 0x00000: 67 64 69 6f  0a                                     gdio.

< 0x00000: 24 52 3a 20  67 64 69 6f  0d 0a 20 20  44 61 74 61  $R: gdi
+o..  Data
< 0x00010: 49 6e 4f 75  74 2c 20 44  53 4b 31 2c  20 43 4d 44  InOut. 
+DSK1. CMD
< 0x00020: 2c 20 53 42  46 2b 4e 4d  45 41 2c 20  28 6f 6e 29  . SBF+N
+MEA. (on)
< 0x00030: 0d 0a 20 20  44 61 74 61  49 6e 4f 75  74 2c 20 43  ..  Dat
+aInOut. C
< 0x00040: 4f 4d 31 2c  20 43 4d 44  2c 20 53 42  46 2b 4e 4d  OM1. CM
+D. SBF+NM
< 0x00050: 45 41 2c 20  28 6f 6e 29  0d 0a 20 20  44 61 74 61  EA. (on
+)..  Data
< 0x00060: 49 6e 4f 75  74 2c 20 43  4f 4d 32 2c  20 43 4d 44  InOut. 
+COM2. CMD
< 0x00070: 2c 20 53 42  46 2b 4e 4d  45 41 2c 20  28 6f 6e 29  . SBF+N
+MEA. (on)
< 0x00080: 0d 0a 20 20  44 61 74 61  49 6e 4f 75  74 2c 20 43  ..  Dat
+aInOut. C
< 0x00090: 4f 4d 33 2c  20 43 4d 44  2c 20 53 42  46 2b 4e 4d  OM3. CM
+D. SBF+NM
< 0x000a0: 45 41 2c 20  28 6f 6e 29  0d 0a 20 20  44 61 74 61  EA. (on
+)..  Data
< 0x000b0: 49 6e 4f 75  74 2c 20 43  4f 4d 34 2c  20 43 4d 44  InOut. 
+COM4. CMD
< 0x000c0: 2c 20 53 42  46 2b 4e 4d  45 41 2c 20  28 6f 6e 29  . SBF+N
+MEA. (on)
< 0x000d0: 0d 0a 20 20  44 61 74 61  49 6e 4f 75  74 2c 20 55  ..  Dat
+aInOut. U
< 0x000e0: 53 42 31 2c  20 43 4d 44  2c 20 53 42  46 2b 4e 4d  SB1. CM
+D. SBF+NM
< 0x000f0: 45 41 2c 20  28 6f 66 66  29 0d 0a 20  20 44 61 74  EA. (of
+f)..  Dat
< 0x00100: 61 49 6e 4f  75 74 2c 20  55 53 42 32  2c 20 43 4d  aInOut.
+ USB2. CM
< 0x00110: 44 2c 20 53  42 46 2b 4e  4d 45 41 2c  20 28 6f 66  D. SBF+
+NMEA. (of
< 0x00120: 66 29 0d 0a  20 20 44 61  74 61 49 6e  4f 75 74 2c  f)..  D
+ataInOut.
< 0x00130: 20 49 50 31  30 2c 20 43  4d 44 2c 20  53 42 46 2b   IP10. 
+CMD. SBF+
< 0x00140: 4e 4d 45 41  2c 20 28 6f  66 66 29 0d  0a 20 20 44  NMEA. (
+off)..  D
< 0x00150: 61 74 61 49  6e 4f 75 74  2c 20 49 50  31 31 2c 20  ataInOu
+t. IP11. 
< 0x00160: 43 4d 44 2c  20 53 42 46  2b 4e 4d 45  41 2c 20 28  CMD. SB
+F+NMEA. (
< 0x00170: 6f 66 66 29  0d 0a 20 20  44 61 74 61  49 6e 4f 75  off).. 
+ DataInOu
< 0x00180: 74 2c 20 49  50 31 32 2c  20 43 4d 44  2c 20 53 42  t. IP12
+. CMD. SB
< 0x00190: 46 2b 4e 4d  45 41 2c 20  28 6f 6e 29  0d 0a 20 20  F+NMEA.
+ (on)..  
< 0x001a0: 44 61 74 61  49 6e 4f 75  74 2c 20 49  50 31 33 2c  DataInO
+ut. IP13.
< 0x001b0: 20 43 4d 44  2c 20 53 42  46 2b 4e 4d  45 41 2c 20   CMD. S
+BF+NMEA. 
< 0x001c0: 28 6f 66 66  29 0d 0a 20  20 44 61 74  61 49 6e 4f  (off)..
+  DataInO
< 0x001d0: 75 74 2c 20  49 50 31 34  2c 20 43 4d  44 2c 20 53  ut. IP1
+4. CMD. S
< 0x001e0: 42 46 2b 4e  4d 45 41 2c  20 28 6f 66  66 29 0d 0a  BF+NMEA
+. (off)..
< 0x001f0: 20 20 44 61  74 61 49 6e  4f 75 74 2c  20 49 50 31    DataI
+nOut. IP1
< 0x00200: 35 2c 20 43  4d 44 2c 20  53 42 46 2b  4e 4d 45 41  5. CMD.
+ SBF+NMEA
< 0x00210: 2c 20 28 6f  66 66 29 0d  0a 20 20 44  61 74 61 49  . (off)
+..  DataI
< 0x00220: 6e 4f 75 74  2c 20 49 50  31 36 2c 20  43 4d 44 2c  nOut. I
+P16. CMD.
< 0x00230: 20 53 42 46  2b 4e 4d 45  41 2c 20 28  6f 66 66 29   SBF+NM
+EA. (off)
< 0x00240: 0d 0a 20 20  44 61 74 61  49 6e 4f 75  74 2c 20 49  ..  Dat
+aInOut. I
< 0x00250: 50 31 37 2c  20 43 4d 44  2c 20 53 42  46 2b 4e 4d  P17. CM
+D. SBF+NM
< 0x00260: 45 41 2c 20  28 6f 66 66  29 0d 0a 49  50 31 32 3e  EA. (of
+f)..IP12>

[download]
Debug output with response after sending an extra return 
> 0x00000: 53 53 53 53  53 53 53 53  53 53 0a                  SSSSSSS
+SSS.

> 0x00000: 0a                                                  .

< 0x00000: 49 50 31 37  3e                                     IP17>

> 0x00000: 0a                                                  .

< 0x00000: 49 50 31 37  3e                                     IP17>

> 0x00000: 67 64 69 6f  0a                                     gdio.

< 0x00000: 49 50 31 37  3e                                     IP17>

> 0x00000: 0a                                                  .

< 0x00000: 24 52 3a 20  67 64 69 6f  0d 0a 20 20  44 61 74 61  $R: gdi
+o..  Data
< 0x00010: 49 6e 4f 75  74 2c 20 44  53 4b 31 2c  20 43 4d 44  InOut. 
+DSK1. CMD
< 0x00020: 2c 20 53 42  46 2b 4e 4d  45 41 2c 20  28 6f 6e 29  . SBF+N
+MEA. (on)
< 0x00030: 0d 0a 20 20  44 61 74 61  49 6e 4f 75  74 2c 20 43  ..  Dat
+aInOut. C
< 0x00040: 4f 4d 31 2c  20 43 4d 44  2c 20 53 42  46 2b 4e 4d  OM1. CM
+D. SBF+NM
< 0x00050: 45 41 2c 20  28 6f 6e 29  0d 0a 20 20  44 61 74 61  EA. (on
+)..  Data
< 0x00060: 49 6e 4f 75  74 2c 20 43  4f 4d 32 2c  20 43 4d 44  InOut. 
+COM2. CMD
< 0x00070: 2c 20 53 42  46 2b 4e 4d  45 41 2c 20  28 6f 6e 29  . SBF+N
+MEA. (on)
< 0x00080: 0d 0a 20 20  44 61 74 61  49 6e 4f 75  74 2c 20 43  ..  Dat
+aInOut. C
< 0x00090: 4f 4d 33 2c  20 43 4d 44  2c 20 53 42  46 2b 4e 4d  OM3. CM
+D. SBF+NM
< 0x000a0: 45 41 2c 20  28 6f 6e 29  0d 0a 20 20  44 61 74 61  EA. (on
+)..  Data
< 0x000b0: 49 6e 4f 75  74 2c 20 43  4f 4d 34 2c  20 43 4d 44  InOut. 
+COM4. CMD
< 0x000c0: 2c 20 53 42  46 2b 4e 4d  45 41 2c 20  28 6f 6e 29  . SBF+N
+MEA. (on)
< 0x000d0: 0d 0a 20 20  44 61 74 61  49 6e 4f 75  74 2c 20 55  ..  Dat
+aInOut. U
< 0x000e0: 53 42 31 2c  20 43 4d 44  2c 20 53 42  46 2b 4e 4d  SB1. CM
+D. SBF+NM
< 0x000f0: 45 41 2c 20  28 6f 66 66  29 0d 0a 20  20 44 61 74  EA. (of
+f)..  Dat
< 0x00100: 61 49 6e 4f  75 74 2c 20  55 53 42 32  2c 20 43 4d  aInOut.
+ USB2. CM
< 0x00110: 44 2c 20 53  42 46 2b 4e  4d 45 41 2c  20 28 6f 66  D. SBF+
+NMEA. (of
< 0x00120: 66 29 0d 0a  20 20 44 61  74 61 49 6e  4f 75 74 2c  f)..  D
+ataInOut.
< 0x00130: 20 49 50 31  30 2c 20 43  4d 44 2c 20  53 42 46 2b   IP10. 
+CMD. SBF+
< 0x00140: 4e 4d 45 41  2c 20 28 6f  66 66 29 0d  0a 20 20 44  NMEA. (
+off)..  D
< 0x00150: 61 74 61 49  6e 4f 75 74  2c 20 49 50  31 31 2c 20  ataInOu
+t. IP11. 
< 0x00160: 43 4d 44 2c  20 53 42 46  2b 4e 4d 45  41 2c 20 28  CMD. SB
+F+NMEA. (
< 0x00170: 6f 66 66 29  0d 0a 20 20  44 61 74 61  49 6e 4f 75  off).. 
+ DataInOu
< 0x00180: 74 2c 20 49  50 31 32 2c  20 43 4d 44  2c 20 53 42  t. IP12
+. CMD. SB
< 0x00190: 46 2b 4e 4d  45 41 2c 20  28 6f 66 66  29 0d 0a 20  F+NMEA.
+ (off).. 
< 0x001a0: 20 44 61 74  61 49 6e 4f  75 74 2c 20  49 50 31 33   DataIn
+Out. IP13
< 0x001b0: 2c 20 43 4d  44 2c 20 53  42 46 2b 4e  4d 45 41 2c  . CMD. 
+SBF+NMEA.
< 0x001c0: 20 28 6f 66  66 29 0d 0a  20 20 44 61  74 61 49 6e   (off).
+.  DataIn
< 0x001d0: 4f 75 74 2c  20 49 50 31  34 2c 20 43  4d 44 2c 20  Out. IP
+14. CMD. 
< 0x001e0: 53 42 46 2b  4e 4d 45 41  2c 20 28 6f  66 66 29 0d  SBF+NME
+A. (off).
< 0x001f0: 0a 20 20 44  61 74 61 49  6e 4f 75 74  2c 20 49 50  .  Data
+InOut. IP
< 0x00200: 31 35 2c 20  43 4d 44 2c  20 53 42 46  2b 4e 4d 45  15. CMD
+. SBF+NME
< 0x00210: 41 2c 20 28  6f 66 66 29  0d 0a 20 20  44 61 74 61  A. (off
+)..  Data
< 0x00220: 49 6e 4f 75  74 2c 20 49  50 31 36 2c  20 43 4d 44  InOut. 
+IP16. CMD
< 0x00230: 2c 20 53 42  46 2b 4e 4d  45 41 2c 20  28 6f 66 66  . SBF+N
+MEA. (off
< 0x00240: 29 0d 0a 20  20 44 61 74  61 49 6e 4f  75 74 2c 20  )..  Da
+taInOut. 
< 0x00250: 49 50 31 37  2c 20 43 4d  44 2c 20 53  42 46 2b 4e  IP17. C
+MD. SBF+N
< 0x00260: 4d 45 41 2c  20 28 6f 6e  29 0d 0a 49  50 31 37 3e  MEA. (o
+n)..IP17>

[download]

In reply to Net::Telnet inconsistent output of ->cmd? by popijopi

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