(Perl) SSH -- Running Commands that Prompt for Additional Input, such as "su"

Demonstrates how to run a shell command via SSH where the shell command prompts for additional input from the client. This example demonstrates "su".

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

# This example assumes the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

$ssh = chilkat::CkSsh->new();

# Hostname may be an IP address or hostname:
$hostname = "172.16.16.46";
$port = 22;

$success = $ssh->Connect($hostname,$port);
if ($success != 1) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# If receiving output from a command stalls for more than 5 seconds, then stop waiting.
$ssh->put_IdleTimeoutMs(5000);

$success = $ssh->AuthenticatePw("myLogin","myPassword");
if ($success != 1) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# Open a session channel. 
$channelNum = $ssh->OpenSessionChannel();
if ($channelNum < 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# Request a pseudo-terminal
$termType = "dumb";
$widthInChars = 120;
$heightInChars = 40;
$pixWidth = 0;
$pixHeight = 0;
$success = $ssh->SendReqPty($channelNum,$termType,$widthInChars,$heightInChars,$pixWidth,$pixHeight);
if ($success != 1) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# Start a shell on the channel:
$success = $ssh->SendReqShell($channelNum);
if ($success != 1) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# Send the su command.
# (The SSH server I'm using for testing is a Linux Ubuntu
# system running OpenSSH.  It is important in this case to send a bare-LF
# and not a CRLF.)
$cmd = "su\n";
$success = $ssh->ChannelSendString($channelNum,$cmd,"ansi");
if ($success != 1) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# Read until we get the prompt for the password:
$success = $ssh->ChannelReceiveUntilMatch($channelNum,"Password:","ansi",1);
if ($success != 1) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# Display what we've received so far:
print $ssh->getReceivedText($channelNum,"ansi") . "\r\n";

# Send the password. (This is the equivalent of typing at the shell prompt.)
# Again, make sure it uses a bare-LF and not a CRLF.

$password = "myPassword\n";
$success = $ssh->ChannelSendString($channelNum,$password,"ansi");
if ($success != 1) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# Read the response until we get the shell prompt (assuming it's successful)
# In my case, the shell prompt is: "chilkat@vivoMini64:~$ "
$myShellPrompt = 'chilkat@vivoMini64:~$';
# It will be different in your case.
$success = $ssh->ChannelReceiveUntilMatch($channelNum,$myShellPrompt,"ansi",1);
if ($success != 1) {
    # Check the last-error information and the session log...
    print $ssh->lastErrorText() . "\r\n";
    # Check to see what was received.  
    print $ssh->getReceivedText($channelNum,"ansi") . "\r\n";
    exit;
}

# Display what we've received so far.  This clears
# the internal receive buffer, which is important. 
# After we send the command, we'll be reading until
# the next command prompt.  If the command prompt
# is already in the internal receive buffer, we'll think we're
# already finished...
print $ssh->getReceivedText($channelNum,"ansi") . "\r\n";

# Send a command.  In this case, we are sending the "ls" command:
$cmd = "ls\n";
$success = $ssh->ChannelSendString($channelNum,$cmd,"ansi");
if ($success != 1) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# Read until the next command prompt:
$success = $ssh->ChannelReceiveUntilMatch($channelNum,$myShellPrompt,"ansi",1);
if ($success != 1) {
    # Check the last-error information and the session log...
    print $ssh->lastErrorText() . "\r\n";
    # Check to see what was received.  
    print $ssh->getReceivedText($channelNum,"ansi") . "\r\n";
    exit;
}

# Display the command output:
print $ssh->getReceivedText($channelNum,"ansi") . "\r\n";

# You may continue sending additional commands.
# The technique is: send the command, read until the next command prompt,
# and then fetch/clear the internal receive buffer.

# We're done, so shut it down..

# Send an EOF.  This tells the server that no more data will 
# be sent on this channel.  The channel remains open, and
# the SSH client may still receive output on this channel.
$success = $ssh->ChannelSendEof($channelNum);
if ($success != 1) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# Close the channel:
$success = $ssh->ChannelSendClose($channelNum);
if ($success != 1) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

# Disconnect
$ssh->Disconnect();