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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Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

# 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.

my $ssh = Chilkat2::Ssh->new;

my $sshPort = 22;
my $success = $ssh->Connect('ssh.example.com', $sshPort);
if (!$success) {
    print $ssh->LastErrorText, "\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.
my $password = 'mySshPassword';

$success = $ssh->AuthenticatePw('mySshLogin', $password);
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

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

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

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

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

$ssh->Disconnect();