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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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Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

#  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-Object Chilkat.Ssh

$sshPort = 22
$success = $ssh.Connect("ssh.example.com",$sshPort)
if ($success -eq $false) {
    $($ssh.LastErrorText)
    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 -eq $false) {
    $($ssh.LastErrorText)
    exit
}

#  Open a session channel.  A negative return value indicates failure.
$channelNum = $ssh.OpenSessionChannel()
if ($channelNum -lt 0) {
    $($ssh.LastErrorText)
    exit
}

$success = $ssh.SendReqExec($channelNum,"uname -a")
if ($success -eq $false) {
    $($ssh.LastErrorText)
    exit
}

#  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.
$success = $ssh.ChannelReceiveToClose($channelNum)
if ($success -eq $false) {
    $($ssh.LastErrorText)
    exit
}

$output = $ssh.GetReceivedText($channelNum,"utf-8")
if ($ssh.LastMethodSuccess -eq $false) {
    $($ssh.LastErrorText)
    exit
}

$($output)

#  Release the retained local resources.  This does not send EOF or CLOSE.
$ssh.ChannelRelease($channelNum)

$ssh.Disconnect()