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 session channel. This is not a separate TCP/IP connection -- it's simply a new session channel on the existing connection. The sequence of Chilkat SSH calls would look like this:

Connect
AuthenticatePw (or AuthenticatePk)

OpenSessionChannel
SendReqExec
<retrieve command output...>
SendChannelClose
ChannelReceiveToClose (to make sure all remaining output is received)

OpenSessionChannel
SendReqExec
<retrieve command output...>
SendChannelClose
ChannelReceiveToClose (to make sure all remaining output is received)

...

OpenSessionChannel
SendReqExec
<retrieve command output...>
SendChannelClose
ChannelReceiveToClose (to make sure all remaining output is received)

Disconnect

Download Chilkat 32-bit SSH / SFTP ActiveX (.msi)

Download All 32-bit Chilkat ActiveX Components (.zip)

Download All 64-bit Chilkat ActiveX Components (.zip)

uses
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
    Dialogs, StdCtrls,
    CHILKATRSALib_TLB,
    CHILKATSSHLib_TLB,
    OleCtrls;

...

procedure TForm1.Button1Click(Sender: TObject);
var
ssh: TChilkatSsh;
success: Integer;
hostname: String;
port: Integer;
channelNum: Integer;
cmd: String;
n: Integer;
pollTimeoutMs: Integer;
cmdOutput: String;

begin
//  Important: It is helpful to send the contents of the
//  ssh.LastErrorText property when requesting support.

ssh := TChilkatSsh.Create(Self);

//  Any string automatically begins a fully-functional 30-day trial.
success := ssh.UnlockComponent('Anything for 30-day trial');
if (success <> 1) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

//  Connect to an SSH server:

//  Hostname may be an IP address or hostname:
hostname := '192.168.1.108';
port := 22;

success := ssh.Connect(hostname,port);
if (success <> 1) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

//  Wait a max of 5 seconds when reading responses..
ssh.IdleTimeoutMs := 5000;

//  Authenticate using login/password:
success := ssh.AuthenticatePw('myLogin','myPassword');
if (success <> 1) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

//  Open a session channel.  (It is possible to have multiple
//  session channels open simultaneously.)

channelNum := ssh.OpenSessionChannel();
if (channelNum < 0) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

//  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

cmd := 'ls -al' + lf;
success := ssh.SendReqExec(channelNum,cmd);
if (success <> 1) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

//  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.

pollTimeoutMs := 2000;
n := ssh.ChannelReadAndPoll(channelNum,pollTimeoutMs);
if (n < 0) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

//  Close the channel:
success := ssh.ChannelSendClose(channelNum);
if (success <> 1) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

//  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 <> 1) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

//  Let's pickup the accumulated output of the command:

cmdOutput := ssh.GetReceivedText(channelNum,'ansi');
if (Length(cmdOutput) = 0 ) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

//  Display the remote shell's command output:
Memo1.Lines.Add(cmdOutput);
Memo1.Lines.Add('----');

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

channelNum := ssh.OpenSessionChannel();
if (channelNum < 0) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

cmd := 'nslookup chilkatsoft.com' + lf;
success := ssh.SendReqExec(channelNum,cmd);
if (success <> 1) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

pollTimeoutMs := 2000;
n := ssh.ChannelReadAndPoll(channelNum,pollTimeoutMs);
if (n < 0) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

success := ssh.ChannelSendClose(channelNum);
if (success <> 1) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

success := ssh.ChannelReceiveToClose(channelNum);
if (success <> 1) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

cmdOutput := ssh.GetReceivedText(channelNum,'ansi');
if (Length(cmdOutput) = 0 ) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add(cmdOutput);

//  Disconnect
ssh.Disconnect();
end;