Getting variable sized reapones using Net::SSH2

essej1 has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to read the output of a command issued using Net::SSH2. For some reason if I do not set the buffer size in the $chan2->read to close to the length of result the command does not finish. The output length is varies from about 20 bytes to over 2048. If I turn on debug ($ssh2->debug(1);) I see bytes being read but no completion. I've tried the two blocking's (ssh and channel) to no avail. I have similar issues with the write and exec options. Is there a better way to do this ? Keep in mind that I'm not the most powerful Perl programmer. And no I can't use expect. Sample code:

  #!/opt/csw/bin/perl

  use strict;
  use warnings;
  use Net::SSH2;

  use constant BUFLEN => 10_0000;

  my $host = "<name or IP>";
  my $user = "<ID>";
  my $pass = "<password>";

  my $buf;

  my $ssh2 = Net::SSH2->new();
  my $ok   = 1;

  print "==> $host\n";
  $ssh2->connect($host) or $ok = 0;

  if ( !$ok ) {
      print "Probable telnet\n";
      exit(1);
  }

  if ( !$ssh2->auth_password( $user, $pass ) ) {
      print "==> 4 pass fail\n";
      exit(1);
  }

  my $chan2 = $ssh2->channel();
  $chan2->shell();
  print $chan2 ("term len 0\n");
  $chan2->read( $buf, BUFLEN );
  print $buf;

  print $chan2 ("dir\n");
  $chan2->read( $buf, BUFLEN );
  print $buf;
[download]

Comment on Getting variable sized reapones using Net::SSH2 Download Code

Replies are listed 'Best First'.
Re: Getting variable sized reapones using Net::SSH2 by Illuminatus (Curate) on Sep 06, 2012 at 17:58 UTC
It seems that the read method is exact; if you're blocking, then it will wait for as many chars as you ask for. There is an undocumented method in Channel called READLINE. Changing your last 3 lines thusly: `my @buf; print $chan2 ("ls -l\n"); @buf = $chan2->READLINE(); print @buf;` [download] and keeping the buflen large (at 10K) gave me the results without hanging. fnord	[reply] [d/l]
Re^2: Getting variable sized reapones using Net::SSH2 by essej1 (Novice) on Sep 06, 2012 at 20:17 UTC
Thanks. It works like a champ. Got to love undocumented features. While messing around I also found this may also work. I think your's is probably better. `print $chan2 "\ndir\n"; while (<$chan2>) { print "$_"; }` [download] Paradise: Florida, full tank of gas, no appointments.	[reply] [d/l]


laziness, impatience, and hubris
	PerlMonks