Get Text Received on the SSH stderr Buffer

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Demonstrates the Chilkat Ssh.GetReceivedStderrText method, which decodes and returns the text accumulated in a channel's separate stderr buffer. The first argument is the channel number and the second is the charset. The stderr buffer is cleared after the text is returned.

Background: This is only meaningful when StderrToStdout is false, which keeps error output in its own buffer instead of merging it into the normal receive buffer. Separating the two lets a program parse a command's real output cleanly while still capturing diagnostics — important because many Unix tools write warnings to stderr that would otherwise corrupt the parsed result. With merging enabled, this buffer stays empty and the text appears via GetReceivedText instead.

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#include <C_CkSsh.h>

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

    success = FALSE;

    //  Demonstrates the Ssh.GetReceivedStderrText method, which decodes and returns the text in a
    //  channel's separate stderr buffer.  The 1st argument is the channel number and the 2nd is the
    //  charset.  The stderr buffer is cleared after the text is returned.

    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;
    }

    //  Keep stderr in its own buffer rather than merging it into the normal receive buffer.
    CkSsh_putStderrToStdout(ssh,FALSE);

    channelNum = CkSsh_OpenSessionChannel(ssh);
    if (channelNum < 0) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    //  Run a command that writes to both stdout and stderr.
    success = CkSsh_SendReqExec(ssh,channelNum,"ls /etc/hosts /no/such/path");
    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;
    }

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

    printf("STDOUT: %s\n",stdoutText);

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

    printf("STDERR: %s\n",stderrText);

    CkSsh_Disconnect(ssh);


    CkSsh_Dispose(ssh);

    }