Delphi DLL

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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var
success: Boolean;
ssh: HCkSsh;
sshPort: Integer;
password: PWideChar;
channelNum: Integer;
exitStatus: Integer;

begin
success := False;

//  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 := CkSsh_Create();

sshPort := 22;
success := CkSsh_Connect(ssh,'ssh.example.com',sshPort);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

//  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 := CkSsh_AuthenticatePw(ssh,'mySshLogin',password);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

channelNum := CkSsh_OpenSessionChannel(ssh);
if (channelNum < 0) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

success := CkSsh_SendReqExec(ssh,channelNum,'grep -q root /etc/passwd');
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

//  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_putReadTimeoutMs(ssh,15000);

success := CkSsh_ChannelReceiveToClose(ssh,channelNum);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

//  Retrieve the exit status immediately, before calling unrelated SSH methods or releasing the
//  channel, because the completed channel record can be discarded.
if (CkSsh_ChannelReceivedExitStatus(ssh,channelNum)) then
  begin
    exitStatus := CkSsh_GetChannelExitStatus(ssh,channelNum);
    Memo1.Lines.Add('Exit status: ' + IntToStr(exitStatus));

    //  By convention, 0 means the remote command succeeded.
    if (exitStatus = 0) then
      begin
        Memo1.Lines.Add('The remote command succeeded.');
      end
    else
      begin
        Memo1.Lines.Add('The remote command reported a failure.');
      end;
  end;

CkSsh_Disconnect(ssh);

CkSsh_Dispose(ssh);