(.NET Core C#) Multiple SendReqExec on Same Connection

Shows how to execute a series of commands on an SSH server and retrieve each command's output (using SendReqExec). Each call to SendReqExec requires its own logical channel. This is not a separate SSH connection -- it's simply a new session channel on the existing SSH connection.

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// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Chilkat.Ssh ssh = new Chilkat.Ssh();

// Hostname may be an IP address or domain:
string hostname = "172.16.16.46";
int port = 22;

bool success = ssh.Connect(hostname,port);
if (success == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// If receiving output from a command stalls for more than 5 seconds, then stop waiting.
ssh.IdleTimeoutMs = 5000;

// Authenticate using login/password:
success = ssh.AuthenticatePw("myLogin","myPassword");
if (success == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Open a session channel.  (It is possible to have multiple
// session channels open simultaneously.)
int channelNum = ssh.OpenSessionChannel();
if (channelNum < 0) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Request a directory listing on the remote server:
// If your server is Linux/UNIX, change the string from "dir" to "ls"
// Note: Some SSH servers require a CRLF instead of a bare-LF
string cmd = "ls -al\n";
success = ssh.SendReqExec(channelNum,cmd);
if (success == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Read whatever output may already be available on the
// SSH connection.  ChannelReadAndPoll returns the number of bytes
// that are available in the channel's internal buffer that
// are ready to be "picked up" by calling GetReceivedText
// or GetReceivedData.
// A return value of -1 indicates failure.
// A return value of -2 indicates a failure via timeout.

// The ChannelReadAndPoll method waits
// for data to arrive on the connection usingi the IdleTimeoutMs
// property setting.  Once the first data arrives, it continues
// reading but instead uses the pollTimeoutMs passed in the 2nd argument:
// A return value of -2 indicates a timeout where no data is received.
int pollTimeoutMs = 2000;
int n = ssh.ChannelReadAndPoll(channelNum,pollTimeoutMs);
if (n < 0) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Close the channel:
success = ssh.ChannelSendClose(channelNum);
if (success == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Perhaps we did not receive all of the commands output.
// To make sure,  call ChannelReceiveToClose to accumulate any remaining
// output until the server's corresponding "channel close" is received.
success = ssh.ChannelReceiveToClose(channelNum);
if (success == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Get the accumulated output of the command:
string cmdOutput;
cmdOutput = ssh.GetReceivedText(channelNum,"ansi");
if (ssh.LastMethodSuccess == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Display the remote shell's command output:
Debug.WriteLine(cmdOutput);
Debug.WriteLine("----");

// -----------------------------------------------------------------
// Now for the 2nd SendReqExe (on the same connection,
// but on a separate logical channel).
// -----------------------------------------------------------------

channelNum = ssh.OpenSessionChannel();
if (channelNum < 0) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

cmd = "nslookup chilkatsoft.com\n";
success = ssh.SendReqExec(channelNum,cmd);
if (success == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

pollTimeoutMs = 2000;
n = ssh.ChannelReadAndPoll(channelNum,pollTimeoutMs);
if (n < 0) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

success = ssh.ChannelSendClose(channelNum);
if (success == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

success = ssh.ChannelReceiveToClose(channelNum);
if (success == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

cmdOutput = ssh.GetReceivedText(channelNum,"ansi");
if (ssh.LastMethodSuccess == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

Debug.WriteLine(cmdOutput);