Visual FoxPro

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.

Chilkat Visual FoxPro Downloads

Download Chilkat for Visual FoxPro

Visual FoxPro

LOCAL lnSuccess
LOCAL loSsh
LOCAL lnSshPort
LOCAL lcPassword
LOCAL lnChannelNum

lnSuccess = 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.

loSsh = CreateObject('Chilkat.Ssh')

lnSshPort = 22
lnSuccess = loSsh.Connect("ssh.example.com",lnSshPort)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

*  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.
lcPassword = "mySshPassword"

lnSuccess = loSsh.AuthenticatePw("mySshLogin",lcPassword)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

*  Open a session channel.  A negative return value indicates failure.
lnChannelNum = loSsh.OpenSessionChannel()
IF (lnChannelNum < 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

IF (loSsh.ChannelIsOpen(lnChannelNum)) THEN
    ? "The channel is open."
ELSE
    ? "The channel is not open."
ENDIF

*  Send CLOSE, which immediately marks the channel locally closed.
lnSuccess = loSsh.ChannelSendClose(lnChannelNum)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

IF (loSsh.ChannelIsOpen(lnChannelNum)) THEN
    ? "Still open."
ELSE
    ? "The channel is now closed."
ENDIF

loSsh.Disconnect()

RELEASE loSsh