Xbase++

Collect Completed SSH Commands with QuickCmdCheck

Demonstrates the Chilkat Ssh.QuickCmdCheck method, which waits for any command started by QuickCmdSend to complete. The only argument is the poll timeout in milliseconds; 0 performs a nonblocking check. It returns the channel number of a completed command, -1 when commands are still pending but none finished before the timeout, or -2 when no quick commands remain or an error occurred.

Background: This is the collection half of the concurrent pattern. Each completed channel is reported only once, so looping until -2 drains every outstanding command exactly once. Distinguish the two negative values carefully: -1 simply means "still working, ask again," while -2 means there is nothing left to wait for — or that the connection failed, so check LastErrorText when the distinction matters. Manually opened exec channels are not reported here.

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LOCAL nSuccess
LOCAL oSsh
LOCAL nSshPort
LOCAL cPassword
LOCAL nChannel1
LOCAL nChannel2
LOCAL nPollTimeoutMs
LOCAL nCompletedChannel
LOCAL cOutput

nSuccess := 0

//  Demonstrates the Ssh.QuickCmdCheck method, which waits for any command started by
//  QuickCmdSend to complete.  The only argument is the poll timeout in milliseconds; 0 performs
//  a nonblocking check.

oSsh := CreateObject("Chilkat.Ssh")

nSshPort := 22
nSuccess := oSsh:Connect("ssh.example.com", nSshPort)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
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.
cPassword := "mySshPassword"

nSuccess := oSsh:AuthenticatePw("mySshLogin", cPassword)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  Start two commands that will finish at different times.
nChannel1 := oSsh:QuickCmdSend("sleep 2; echo first done")
IF (nChannel1 < 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

nChannel2 := oSsh:QuickCmdSend("echo second done")
IF (nChannel2 < 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  Collect the results as they complete.  The return value is the channel number of a completed
//  command, -1 if commands are still pending but none finished before the timeout, or -2 when
//  no quick commands remain (or an error occurred).
nPollTimeoutMs := 5000
nCompletedChannel := oSsh:QuickCmdCheck(nPollTimeoutMs)
DO WHILE nCompletedChannel != -2
    IF (nCompletedChannel >= 0)
        cOutput := oSsh:GetReceivedText(nCompletedChannel, "utf-8")
        IF (oSsh:LastMethodSuccess == 0)
            ? oSsh:LastErrorText
            oSsh:destroy()
            RETURN
        ENDIF

        ? "Channel " + Str(nCompletedChannel) + " finished: " + cOutput
    ENDIF

    IF (nCompletedChannel == -1)
        ? "Still waiting for a command to finish..."
    ENDIF

    nCompletedChannel := oSsh:QuickCmdCheck(nPollTimeoutMs)
ENDDO

? "All quick commands have been collected."

oSsh:Disconnect()

oSsh:destroy()