Perl

Check Whether an SSH Channel is Open

Demonstrates the Chilkat Ssh.ChannelIsOpen method, which reports whether a channel number identifies a channel Chilkat currently considers open for application I/O. The only argument is the channel number. This example checks the channel before and after sending CLOSE.

Background: Because one SSH connection can carry many channels with independent lifetimes, code that manages several needs a way to ask whether a given one is still usable. This returns false for invalid or nonexistent channel numbers, after a local Disconnect, once remote closure is processed, and immediately after ChannelSendClose — which marks the channel locally closed without waiting for the remote side.

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Perl

use chilkat();

$success = 0;

#  Demonstrates the Ssh.ChannelIsOpen method, which reports whether a channel number identifies
#  a channel Chilkat currently considers open for application I/O.  The only argument is the
#  channel number.

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

$sshPort = 22;
$success = $ssh->Connect("ssh.example.com",$sshPort);
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

#  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";

$success = $ssh->AuthenticatePw("mySshLogin",$password);
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

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

if ($ssh->ChannelIsOpen($channelNum)) {
    print "The channel is open." . "\r\n";
}
else {
    print "The channel is not open." . "\r\n";
}

#  Send CLOSE, which immediately marks the channel locally closed.
$success = $ssh->ChannelSendClose($channelNum);
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

if ($ssh->ChannelIsOpen($channelNum)) {
    print "Still open." . "\r\n";
}
else {
    print "The channel is now closed." . "\r\n";
}

$ssh->Disconnect();