Get the Number of Bytes Buffered on an SSH Channel

See more SSH Examples

Demonstrates the Chilkat Ssh.GetReceivedNumBytes method, which returns how many bytes are currently available in a channel's normal receive buffer. The only argument is the channel number. It returns -1 when the channel number is invalid or its retained resources have been released.

Background: This is a non-consuming look at how much is waiting, useful for deciding whether to retrieve now or keep reading, and for reporting progress on a large transfer. It counts only the normal receive buffer — bytes in the separate stderr buffer are excluded when StderrToStdout is false. Note that data received earlier can remain available even after a disconnect, so a positive count does not imply the connection is still up.

Chilkat Go Downloads

Download Chilkat for Go

    success := false

    //  Demonstrates the Ssh.GetReceivedNumBytes method, which returns the number of bytes currently
    //  available in a channel's normal receive buffer.  The only argument is the channel number.
    //  It returns -1 for an invalid channel or one whose resources have been released.

    ssh := chilkat.NewSsh()

    sshPort := 22
    success = ssh.Connect("ssh.example.com",sshPort)
    if success == false {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        return
    }

    //  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 == false {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        return
    }

    channelNum := ssh.OpenSessionChannel()
    if channelNum < 0 {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        return
    }

    success = ssh.SendReqExec(channelNum,"ls -l /tmp")
    if success == false {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        return
    }

    //  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.SetReadTimeoutMs(15000)

    success = ssh.ChannelReceiveToClose(channelNum)
    if success == false {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        return
    }

    //  Find out how much is waiting before retrieving it.
    numBytes := ssh.GetReceivedNumBytes(channelNum)
    if numBytes < 0 {
        fmt.Println("Invalid channel, or its resources were already released.")
        ssh.DisposeSsh()
        return
    }

    fmt.Println("Bytes available: ", numBytes)

    output := ssh.GetReceivedText(channelNum,"utf-8")
    if ssh.LastMethodSuccess() == false {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        return
    }

    fmt.Println(*output)

    ssh.Disconnect()

    ssh.DisposeSsh()