Set an Environment Variable on an SSH Channel

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Demonstrates the Chilkat Ssh.SendReqSetEnv method, which asks the server to set an environment variable for a session channel. The arguments are the channel number, the variable name, and its value. Send these requests before the exec, shell, or subsystem request.

#include <C_CkSsh.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSsh ssh;
    int sshPort;
    const char *password;
    int channelNum;
    const char *output;

    success = FALSE;

    //  Demonstrates the Ssh.SendReqSetEnv method, which asks the server to set an environment
    //  variable for a session channel.  The 1st argument is the channel number, the 2nd is the
    //  variable name, and the 3rd is its value.  Send it before the exec, shell, or subsystem
    //  request.

    ssh = CkSsh_Create();

    sshPort = 22;
    success = CkSsh_Connect(ssh,"ssh.example.com",sshPort);
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        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 = CkSsh_AuthenticatePw(ssh,"mySshLogin",password);
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

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

    //  Set environment variables for the channel.  Multiple variables may be requested.
    success = CkSsh_SendReqSetEnv(ssh,channelNum,"LANG","en_US.UTF-8");
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    success = CkSsh_SendReqSetEnv(ssh,channelNum,"MY_APP_MODE","production");
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    //  Now run the command, which sees the requested environment.
    success = CkSsh_SendReqExec(ssh,channelNum,"echo $MY_APP_MODE");
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        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.
    CkSsh_putReadTimeoutMs(ssh,15000);

    success = CkSsh_ChannelReceiveToClose(ssh,channelNum);
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    output = CkSsh_getReceivedText(ssh,channelNum,"utf-8");
    if (CkSsh_getLastMethodSuccess(ssh) == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    printf("%s\n",output);

    CkSsh_Disconnect(ssh);


    CkSsh_Dispose(ssh);

    }