NAME

SYNOPSIS

        use Net::SSH::Expect;

        #
        # You can do SSH authentication with user-password or without it.
        #

        # Making an ssh connection with user-password authentication
        # 1) construct the object
        my $ssh = Net::SSH::Expect->new (
            host => "myserver.com", 
            password=> 'pass87word', 
            user => 'bnegrao', 
            raw_pty => 1
        );

        # 2) logon to the SSH server using those credentials.
        # test the login output to make sure we had success
        my $login_output = $ssh->login();
        if ($login_output !~ /Welcome/) {
            die "Login has failed. Login output was $login_output";
        }
        
        # - now you know you're logged in - #

        # Starting ssh without password
        # 1) run the constructor
        my $ssh = Net::SSH::Expect->new (
            host => "myserver.com", 
            user => 'bnegrao', 
            raw_pty => 1
        );
        # 2) now start the ssh process
        $ssh->run_ssh() or die "SSH process couldn't start: $!";
        
        # 3) you should be logged on now. Test if you received the remote prompt:
        ($ssh->read_all(2) =~ />\s*\z/) or die "where's the remote prompt?"

        # - now you know you're logged in - #

        # disable terminal translations and echo on the SSH server
        # executing on the server the stty command:
        $ssh->exec("stty raw -echo");

        # runs arbitrary commands and print their outputs 
        # (including the remote prompt comming at the end)
        my $ls = $ssh->exec("ls -l /");
        print($ls);
        
        my $who = $ssh->exec("who");
        print ($who);
        
        # When running a command that causes a huge output,
        # lets get the output line by line:
        $ssh->send("find /");   # using send() instead of exec()
        my $line;
        # returns the next line, removing it from the input stream:
        while ( defined ($line = $ssh->read_line()) ) {
            print $line . "\n";  
        }

        # take a look in what is immediately available on the input stream
        print $ssh->peek(0);    # you'll probably see the remote prompt
 
        # the last read_line() on the previous loop will not include the
        # remote prompt that appears at the end of the output, because the prompt
        # doesn't end with a '\n' character. So let's remove the remainder
        # prompt from the input stream:
        $ssh->eat($ssh->peek(0));  # removes whatever is on the input stream now

        # We can also iterate over the output in chunks,
        # printing everything that's available at each 1 second:
        $ssh->send ("find /home");
        my $chunk;
        while ($chunk = $ssh->peek(1)) { # grabs chunks of output each 1 second
            print $ssh->eat($chunk);
        }

        # Now let's run an interactive command, like passwd.
        # This is done combining send() and waitfor() methods together:
        $ssh->send("passwd");
        $ssh->waitfor('password:\s*\z', 1) or die "prompt 'password' not found after 1 second";
        $ssh->send("curren_password");
        $ssh->waitfor(':\s*\z', 1) or die "prompt 'New password:' not found";
        $ssh->send("new_password");
        $ssh->waitfor(':\s*\z', 1) or die "prompt 'Confirm new password:' not found";
        $ssh->send("new_password");

        # check that we have the system prompt again.
        my ($before_match, $match) = $ssh->waitfor('>\s*\z', 1);  # waitfor() in a list context
        die "passwd failed. passwd said '$before_match'." unless ($match);

        # closes the ssh connection
        $ssh->close();

DESCRIPTION

Once an ssh connection was started using the "connect()" method it will remain open until you call the "close()" method. This allows you execute as many commands as you want with the "exec()" method using only one connection. This is a better approach over other ssh wrapper implementations, i.e: Net::SCP, Net::SSH and Net::SCP::Expect, that start a new ssh connection each time a remote command is issued or a file is transfered.

It uses Expect.pm module to interact with the SSH server. A "get_expect()" method is provided so you can obtain the internal "Expect" object connected to the SSH server. Use this only if you have some special need that you can't do with the "exec()" method.

This module was inspired by Net::SCP::Expect <http://search.cpan.org/~djberg/Net-SCP-Expect-0.12/Expect.pm> and by Net::Telnet and some of its methods work the same as these two modules.

    $ssh->exec("stty raw -echo");

EXPORT

CONSTRUCTOR ATTRIBUTES

METHODS

boolean run_ssh() - forks the ssh client process

        # boolean run_ssh() - forks the ssh client process opening an ssh connection to the SSH server.
        #
        #       This method has three roles:
        #       1)      Instantiate a new Expect object configuring it with all the defaults and user-defined
        #               settings.
        #       2)      Define the ssh command line using the defaults and user-defined settings
        #       3)      Fork the ssh process using the spawn() method of the Expect instance we created. 
        #               The SSH connection is established on this step using the user account set in the 'user'
        #               constructor attribute. No password is sent here, that happens only in the login() method.
        #
        #       This method is run internally by the login() method so you don't need to run it yourself
        #       in most of the cases. You'll run this method alone if you had set up public-key authentication 
        #       between the ssh client and the ssh server. In this case you only need to call this method
        #       to have an authenticated ssh connection, you won't call login(). Note that when you 
        #       use public-key authentication you won't need to set the 'password' constructor attribute
        #       but you still need to define the 'user' attribute.
        #       If you don't know how to setup public-key authentication there's a good guide at
        #       http://sial.org/howto/openssh/publickey-auth/
        #               
        # returns:
        #       boolean: 1 if the ssh ran OK or 0 otherwise. In case of failures, use $! to do get info.
    

string login([$login_prompt, $password_prompt] [,$test_success]) - authenticates on the ssh server.

        # string login ([$login_prompt, $password_prompt] [,$test_success]) - authenticates on the ssh server. 
        #       This method responds to the authentication prompt sent by the SSH server. 
        #       You can customize the "Login:" and "Password:" prompts that must be expected by passing their
        #       patterns as arguments to this method, although this method has default values that work to most
        #       SSH servers out there.
        #       It runs the run_ssh() method only if it wasn't run before(), but it'll die
        #       if run_ssh() returns false.
        #
        # param:
        #       $login_prompt: A pattern string used to match the "Login:" prompt. The default 
        #               pattern is qr/ogin:\s*$/
        #
        #       $password_prompt: A pattern string used to match the "Password:" prompt. The default
        #               pattern is qr/[Pp]assword.*?:|[Pp]assphrase.*?:/
        #
        #       $test_success: 0 | 1. if 1, login will do an extra-test to verify if the password
        #               entered was accepted. The test consists in verifying if, after sending the password,
        #               the "Password" prompt shows up again what would indicate that the password was rejected.
        #               This test is disabled by default.
        #
        #       OBS: the number of paramaters passed to this method will tell it what parameters are being passed:
        #       0 parameters: login() : All the default values will be used.
        #       1 parameter:  login(1) : The $test_success parameter is set.
        #       2 parameters: login("Login:", "Password:") : the $login_prompt and $password_prompt parameters are set.
        #       3 parameters: login("Login:", "Password;", 1) : the three parameters received values on this order.
        #
        # returns:
        #       string: whatever the SSH server wrote in my input stream after loging in. This usually is some
        #               welcome message and/or the remote prompt. You could use this string to do your verification
        #               that the login was successful. The content returned is removed from the input stream.
        # dies:
        #       IllegalState: if any of 'host' or 'user' or 'password' fields are unset.
        #       SSHProccessError: if run_ssh() failed to spawn the ssh process
        #       SSHConnectionError: if the connection failed for some reason, like invalid 'host' address or network problems.
    

string exec($cmd [,$timeout]) - executes a command in the remote machine returning its output

exec('command') runs 'command' in the remote machine and returns all the output generated by 'command' into a string.

boolean waitfor($pattern [,$timeout])

        # boolean waitfor ($string [, $timeout, $match_type])
        # This method reads until a pattern or string is found in the input stream.
        # All the characters before and including the match are removed from the input stream.
        # 
        # After waitfor returns, use the methods before(), match() and after() to get the data
        # 'before the match', 'what matched', and 'after the match' respectively.
        #
        # If waitfor returns false, whatever content is on input stream can be accessed with 
        # before(). In this case before() will return the same content as peek(). 
        #
        # params:
        #       $string: a string to be matched. It can be a regular expression or a literal string
        #                        anb its interpretation as one or other depends on $match_type. Default is
        #                        're', what treats $string as a regular expression.
        #
        #       $timeout: the timeout in seconds while waiting for $string
        #
        #       $match_type: match_type affects how $string will be matched:
        #               '-re': means $string is a regular expression.
        #               '-ex': means $string is an "exact match", i.e., will be matched literally.
        #
        # returns: 
        #       boolean: 1 is returned if string was found, 0 otherwise. When the match fails
        #                        waitfor() will only return after waiting $timeout seconds.
        #
        # dies:
        #       SSH_CONNECTION_ABORTED if EOF is found (error type 2)
        #       SSH_PROCESS_ERROR if the ssh process has died (error type 3)
        #       SSH_CONNECTION_ERROR if unknown error (type 4) is found
    

string before() - returns the "before match" data of the last waitfor() call.

When waitfor() matches, if there is any content before the match, this will be returned by before().

If the last waitfor() didn't match, before() will return all the current content on the input stream, just as if you had called peek() with the same timeout.

string match() - returns the "match" data of the last waitfor() call, or undef if didn't match.

string after() - returns the "after match" data of the last waitfor() call, or undef if didn't match.

void close() - terminates the ssh connection

void send($string) - sends $string to the SSH server, returns nothing

Sends the string to the SSH server. If the ssh server process is attached to a pseudo-terminal (this is the default) it is likely that the echo terminal property will be on, what will make the server place the command you just sent in our input stream, i.e., you'll see the command you sent in your next read operation.

To avoid this, try to disable the echo property on the server-side, using

 $ssh->exec("stty -echo");
    

It's also advisable to disable the terminal character convertions on server-side, what will make you sure that every character you sent will be received "as-is" to the other side.

So you'll probably use this to disable character conversions and echo:

 $ssh->exec("stty raw -echo");
    

Of course you're server must support the 'stty' command for that work.

To guarantee that your characters are not converted by your local pseudo-terminal before you send them out, set the constructor option:

        raw_pty => 1
    

And if you don't need a terminal on the server-side at all, set the constructor option bellow to 1:

        no_terminal => 1
    

string peek([$timeout]) - returns what is in the input stream without removing anything

        # peek([$timeout]) - returns what is in the input stream without removing anything
        #       peek() returns what is available on the input stream until $timeout seconds.
        #       If there is data continuosly arriving on the input stream, subsequent calls to peek() 
        #       will return a growing amount of data.
        #
        # dies:
        #       SSH_CONNECTION_ABORTED if EOF is found (error type 2)
        #       SSH_PROCESS_ERROR if the ssh process has died (error type 3)
        #       SSH_CONNECTION_ERROR if unknown error (type 4) is found
    

string eat($string) - removes all the head of the input stream until $string inclusive.

        # string eat($string)- removes all the head of the input stream until $string inclusive.
        #       eat() will only be able to remove the $string if it's currently present on the 
        #       input stream because eat() will wait 0 seconds before removing it.
        #
        #       Use it associated with peek to eat everything that appears on the input stream:
        #
        #       while ($chunk = $exp->eat($exp->peak())) {
        #               print $chunk;
        #       }
        #       
        #       Or use the read_all() method that does the above loop for you returning the accumulated
        #       result.
        #
        # param:
        #       string: a string currently available on the input stream. 
        #               If $string doesn't start in the head, all the content before $string will also
        #               be removed. 
        #
        #               If $string is undef or empty string it will be returned immediately as it.
        #       
        # returns:
        #       string: the removed content or empty string if there is nothing in the input stream.
        # 
        # dies:
        #       SSH_CONNECTION_ABORTED if EOF is found (error type 2)
        #       SSH_PROCESS_ERROR if the ssh process has died (error type 3)
        #       SSH_CONNECTION_ERROR if unknown error (type 4) is found
        #
        # debbuging features:
        #       The following warnings are printed to STDERR if $exp->debug() == 1:
        #               eat() prints a warning is $string wasn't found in the head of the input stream.
        #               eat() prints a warning is $string was empty or undefined.
        #
    

string read_all([$timeout]) - reads and removes all the output from the input stream.

The reading/removing process will be interrupted after $timeout seconds of inactivity on the input stream.

string read_line([$timeout]) - reads the next line from the input stream and returns it.

        # string read_line([$timeout]) - reads the next line from the input stream
        # Read a line of text. A line is considered to be terminated by the 'teminator'
        # character. Default is "\n". Lines can also be ended with "\r" or "\r\n".
        # Remember to adequate this for your system with the terminator() method. 
        # When there are no more lines available, read_line() returns undef. Note that this doen't mean
        # there is no data left on input stream since there can be a string not terminated with the 
        # 'terminator' character, notably the remote prompt could be left there when read_line() returns
        # undef.
        #
        # params:
        #       $timeout: the timeout waiting for a line. Defaults to timeout().
        #
        # returns:
        #       string: a line on the input stream, without the trailing 'terminator' character.
        #                       An empty string indicates that the line read only contained the 'terminator'
        #                       character (an empty line).
        #       undef: when there are no more lines on the input stream.
        #
    

void restart_timeout_upon_receive( 0 | 1 ) - changes the timeout counter behaviour

        # void restart_timeout_upon_receive( 0 | 1 ) - changes the timeout counter behaviour
        # params:
        #       boolean: if true, sets the timeout to "inactivity timeout", if false
        #                       sets it to "absolute timeout".
        # dies:
        #       IllegalParamenter if argument is not given.
    

Expect get_expect() - returns the internal Expect object

SEE ALSO

REPORTING BUGS

AUTHOR

THANKS

COPYRIGHT AND LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.3 or, at your option, any later version of Perl 5 you may have available.