Net::OpenSSH changing directory does not work properly

[Pascal2020]

Hi

I want to use Net::OpenSSH to make life a bit easier in maintaining systems. For this I want to first copy a file to the destination machine and afterwards login to the machine, untar the file to a temp directory and changing the directory to this temporary directory so I can run a script from that directory.

However this fails to work. If I do for instance 'cd /usr/local/ ; ls -la' as system command it works fine. If I first do 'cd /usr/local/' and then a new command 'ls -la' it gives the listing of the login directory. Ergo it does change the directory but it loses the working directory when the next system command is run.

Example code

#!/usr/bin/perl

 use Getopt::Long;
 use Net::SFTP::Foreign;
 use XML::Simple;
 use Net::OpenSSH;

 my $config = XMLin('agama.xml');

 my $debug = 0;
 my $username = '';
 my $password = '';


 GetOptions ('debug' => \$debug, 'file=s' => \$rpmfile, 'username=s' =
+> \$username, 'password=s' => \$password);

 foreach $host (@{$config->{hostname}})
 {
  if ($password eq '') { $ssh = Net::OpenSSH->new($host,user=>$usernam
+e,timeout => 10,strict_mode => 0); }
  else { $ssh = Net::OpenSSH->new($host,user=>$username,password=>$pas
+sword,timeout => 10,strict_mode => 0); }

  $ssh->error and
    die "Couldn't establish SSH connection: ". $ssh->error;

  my $cmd1 = 'cd /usr/local/ ; ls -la';
  my $cmd2 = 'ls -la';

  print "Output cmd1:\n";
  $ssh->system($cmd1) or
        die "remote command failed: " . $ssh->error;
  print "Output cmd2:\n";
  $ssh->system($cmd2) or
        die "remote command failed: " . $ssh->error;

 }

Output:

Output cmd1:
total 96
drwxr-xr-x 12 root root 4096 Dec  6 21:00 .
drwxr-xr-x 15 root root 4096 Dec  6 21:01 ..
drwxr-xr-x  2 root root 4096 Oct  1  2009 bin
drwxr-xr-x  2 root root 4096 Oct  1  2009 etc
drwxr-xr-x  2 root root 4096 Oct  1  2009 games
drwxr-xr-x  2 root root 4096 Oct  1  2009 include
drwxr-xr-x  2 root root 4096 Oct  1  2009 lib
drwxr-xr-x  2 root root 4096 Oct  1  2009 lib64
drwxr-xr-x  2 root root 4096 Oct  1  2009 libexec
drwxr-xr-x  2 root root 4096 Oct  1  2009 sbin
drwxr-xr-x  4 root root 4096 Dec  6 21:00 share
drwxr-xr-x  3 root root 4096 Dec  6 20:10 src
Output cmd2:
total 160
drwxr-x---  7 root root  4096 Dec  7 10:02 .
drwxr-xr-x 25 root root  4096 Dec  7 09:23 ..
-rw-------  1 root root  1270 Dec  6 21:06 anaconda-ks.cfg
-rw-------  1 root root   198 Dec  6 20:11 .bash_history
-rw-r--r--  1 root root    24 Jul 13  2006 .bash_logout
-rw-r--r--  1 root root   191 Jul 13  2006 .bash_profile
-rw-r--r--  1 root root   176 Jul 13  2006 .bashrc
drwxr-xr-x  4 root root  4096 Dec  7 10:02 .cpan
-rw-r--r--  1 root root   100 Jul 13  2006 .cshrc
-rw-r--r--  1 root root 36832 Dec  6 21:06 install.log
-rw-r--r--  1 root root  3686 Dec  6 21:06 install.log.syslog
drwx------  2 root root  4096 Dec  7 10:02 .libnet-openssh-perl
drwx------  2 root root  4096 Dec  7 10:02 .ssh
-rw-r--r--  1 root root   129 Jul 13  2006 .tcshrc

Tested on CentOS 5.7 and RedHat 5.6. Also compiled a new version of OpenSSH on the main and destination machine but unfortunatly the results stay the same.

Can someone tell me what I am doing wrong? Do I need an extra setting or use a different command?

[salva]

This is a FAQ explained on the module documentation (look for "Can't change working directory").

[keszler]

Net::SSH2, unlike Net::OpenSSH, provides a 'shell' method for a persistent connection allowing multiple commands. See A little demo for Net::SSH2 for an example.

[salva]

Net::OpenSSH does also support running a remote shell and it even allows to use Expect to interact with it.

But in my opinion, talking to a shell is harder and less reliable than running simple commands even if they have to be prepended with cd $path && ....

[keszler]

Aha - I overlooked $ssh->open2pty. Thank you.

I agree that for a handful of serial-dependent commands the shell overhead is excessive, but at some point I believe it becomes worthwhile.

[TJPride]

Why not use absolute paths? Not necessarily as elegant, but it works.