PureBasic

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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IncludeFile "CkSsh.pb"

Procedure ChilkatExample()

    success.i = 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.

    ssh.i = CkSsh::ckCreate()
    If ssh.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    sshPort.i = 22
    success = CkSsh::ckConnect(ssh,"ssh.example.com",sshPort)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    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.
    password.s = "mySshPassword"

    success = CkSsh::ckAuthenticatePw(ssh,"mySshLogin",password)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    channelNum.i = CkSsh::ckOpenSessionChannel(ssh)
    If channelNum < 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    success = CkSsh::ckSendReqExec(ssh,channelNum,"grep -q root /etc/passwd")
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    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.
    CkSsh::setCkReadTimeoutMs(ssh, 15000)

    success = CkSsh::ckChannelReceiveToClose(ssh,channelNum)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    ;  Retrieve the exit status immediately, before calling unrelated SSH methods or releasing the
    ;  channel, because the completed channel record can be discarded.
    If CkSsh::ckChannelReceivedExitStatus(ssh,channelNum)
        exitStatus.i = CkSsh::ckGetChannelExitStatus(ssh,channelNum)
        Debug "Exit status: " + Str(exitStatus)

        ;  By convention, 0 means the remote command succeeded.
        If exitStatus = 0
            Debug "The remote command succeeded."
        Else
            Debug "The remote command reported a failure."
        EndIf

    EndIf

    CkSsh::ckDisconnect(ssh)


    CkSsh::ckDispose(ssh)


    ProcedureReturn
EndProcedure