Visual FoxPro

Get the Exit Status of a Remote SSH Command

Demonstrates the Chilkat Ssh.GetChannelExitStatus method, which returns the remote process exit status for a channel. The only argument is the channel number. Call it only after ChannelReceivedExitStatus returns true.

Background: The exit status is how you learn whether a remote command actually succeeded — recall that a successful exec request only means the request was accepted. By Unix convention 0 means success and any nonzero value indicates a failure. Retrieve it promptly after the receive operation and before calling unrelated SSH methods or releasing the channel, since the completed channel record can be discarded.

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LOCAL lnSuccess
LOCAL loSsh
LOCAL lnSshPort
LOCAL lcPassword
LOCAL lnChannelNum
LOCAL lnExitStatus

lnSuccess = 0

*  Demonstrates the Ssh.GetChannelExitStatus method, which returns the remote process exit
*  status for a channel.  The only argument is the channel number.  Call it only after
*  ChannelReceivedExitStatus returns 1.

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

lnChannelNum = loSsh.OpenSessionChannel()
IF (lnChannelNum < 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

lnSuccess = loSsh.SendReqExec(lnChannelNum,"grep -q root /etc/passwd")
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

*  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.
loSsh.ReadTimeoutMs = 15000

lnSuccess = loSsh.ChannelReceiveToClose(lnChannelNum)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

*  Retrieve the exit status immediately, before calling unrelated SSH methods or releasing the
*  channel, because the completed channel record can be discarded.
IF (loSsh.ChannelReceivedExitStatus(lnChannelNum)) THEN
    lnExitStatus = loSsh.GetChannelExitStatus(lnChannelNum)
    ? "Exit status: " + STR(lnExitStatus)

    *  By convention, 0 means the remote command succeeded.
    IF (lnExitStatus = 0) THEN
        ? "The remote command succeeded."
    ELSE
        ? "The remote command reported a failure."
    ENDIF

ENDIF

loSsh.Disconnect()

RELEASE loSsh