PHP

Release an SSH Channel's Local Resources

Demonstrates the Chilkat Ssh.ChannelRelease method, which releases Chilkat's retained local resources for a channel after all output and exit information has been retrieved. The only argument is the channel number.

Background: Chilkat retains a channel's buffered output and exit information after the channel closes, so you can still read a command's final output. That retention costs memory, and a long-running program that opens many channels should release each one when finished with it. Note this is not a channel-closing method — it sends neither EOF nor CLOSE. Retrieve everything you need first, because releasing discards it.

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<?php

use Chilkat2\Ssh;

// Demonstrates the Ssh.ChannelRelease method, which releases Chilkat's retained local resources
// for a channel after all output and exit information has been retrieved.  The only argument is
// the channel number.

$ssh = new Ssh();

$sshPort = 22;
try {
    $ssh->Connect('ssh.example.com', $sshPort);

    // Normally you would not hard-code the password in source.  You should instead obtain it
    // from an interactive prompt, environment variable, or a secrets vault.
    $password = 'mySshPassword';

    $ssh->AuthenticatePw('mySshLogin', $password);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

// Open a session channel.  A negative return value indicates failure.
$channelNum = $ssh->OpenSessionChannel();
if ($channelNum < 0) {
    echo $ssh->LastErrorText, "\n";
    exit;
}

try {
    $ssh->SendReqExec($channelNum, 'uname -a');

    // IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
    // it, this call waits forever if the server never sends channel close.
    $ssh->ReadTimeoutMs = 15000;

    // Retrieve everything of interest before releasing the channel.
    $ssh->ChannelReceiveToClose($channelNum);

    $output = $ssh->GetReceivedText($channelNum, 'utf-8');
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo $output, "\n";

// Release the retained local resources.  This does not send EOF or CLOSE.
$ssh->ChannelRelease($channelNum);

$ssh->Disconnect();