(C) SSH -- Running Commands that Prompt for Additional Input, such as "su"

Demonstrates how to run a shell command via SSH where the shell command prompts for additional input from the client. This example demonstrates "su".

Chilkat C/C++ Library Downloads
MS Visual C/C++ C++ Builder Linux C/C++ Alpine Linux C/C++	MacOS C/C++ iOS C/C++ Android C/C++ MinGW C/C++

#include <C_CkSsh.h>

void ChilkatSample(void)
    {
    HCkSsh ssh;
    const char *hostname;
    int port;
    BOOL success;
    int channelNum;
    const char *termType;
    int widthInChars;
    int heightInChars;
    int pixWidth;
    int pixHeight;
    const char *cmd;
    const char *password;
    const char *myShellPrompt;

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

    ssh = CkSsh_Create();

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

    success = CkSsh_Connect(ssh,hostname,port);
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

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

    success = CkSsh_AuthenticatePw(ssh,"myLogin","myPassword");
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    // Open a session channel. 
    channelNum = CkSsh_OpenSessionChannel(ssh);
    if (channelNum < 0) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    // Request a pseudo-terminal
    termType = "dumb";
    widthInChars = 120;
    heightInChars = 40;
    pixWidth = 0;
    pixHeight = 0;
    success = CkSsh_SendReqPty(ssh,channelNum,termType,widthInChars,heightInChars,pixWidth,pixHeight);
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    // Start a shell on the channel:
    success = CkSsh_SendReqShell(ssh,channelNum);
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    // Send the su command.
    // (The SSH server I'm using for testing is a Linux Ubuntu
    // system running OpenSSH.  It is important in this case to send a bare-LF
    // and not a CRLF.)
    cmd = "su\n";
    success = CkSsh_ChannelSendString(ssh,channelNum,cmd,"ansi");
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    // Read until we get the prompt for the password:
    success = CkSsh_ChannelReceiveUntilMatch(ssh,channelNum,"Password:","ansi",TRUE);
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    // Display what we've received so far:
    printf("%s\n",CkSsh_getReceivedText(ssh,channelNum,"ansi"));

    // Send the password. (This is the equivalent of typing at the shell prompt.)
    // Again, make sure it uses a bare-LF and not a CRLF.

    password = "myPassword\n";
    success = CkSsh_ChannelSendString(ssh,channelNum,password,"ansi");
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    // Read the response until we get the shell prompt (assuming it's successful)
    // In my case, the shell prompt is: "chilkat@vivoMini64:~$ "
    myShellPrompt = "chilkat@vivoMini64:~$";
    // It will be different in your case.
    success = CkSsh_ChannelReceiveUntilMatch(ssh,channelNum,myShellPrompt,"ansi",TRUE);
    if (success != TRUE) {
        // Check the last-error information and the session log...
        printf("%s\n",CkSsh_lastErrorText(ssh));
        // Check to see what was received.  
        printf("%s\n",CkSsh_getReceivedText(ssh,channelNum,"ansi"));
        CkSsh_Dispose(ssh);
        return;
    }

    // Display what we've received so far.  This clears
    // the internal receive buffer, which is important. 
    // After we send the command, we'll be reading until
    // the next command prompt.  If the command prompt
    // is already in the internal receive buffer, we'll think we're
    // already finished...
    printf("%s\n",CkSsh_getReceivedText(ssh,channelNum,"ansi"));

    // Send a command.  In this case, we are sending the "ls" command:
    cmd = "ls\n";
    success = CkSsh_ChannelSendString(ssh,channelNum,cmd,"ansi");
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    // Read until the next command prompt:
    success = CkSsh_ChannelReceiveUntilMatch(ssh,channelNum,myShellPrompt,"ansi",TRUE);
    if (success != TRUE) {
        // Check the last-error information and the session log...
        printf("%s\n",CkSsh_lastErrorText(ssh));
        // Check to see what was received.  
        printf("%s\n",CkSsh_getReceivedText(ssh,channelNum,"ansi"));
        CkSsh_Dispose(ssh);
        return;
    }

    // Display the command output:
    printf("%s\n",CkSsh_getReceivedText(ssh,channelNum,"ansi"));

    // You may continue sending additional commands.
    // The technique is: send the command, read until the next command prompt,
    // and then fetch/clear the internal receive buffer.

    // We're done, so shut it down..

    // Send an EOF.  This tells the server that no more data will 
    // be sent on this channel.  The channel remains open, and
    // the SSH client may still receive output on this channel.
    success = CkSsh_ChannelSendEof(ssh,channelNum);
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    // Close the channel:
    success = CkSsh_ChannelSendClose(ssh,channelNum);
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    // Disconnect
    CkSsh_Disconnect(ssh);


    CkSsh_Dispose(ssh);

    }