C++

Get Text Received on the SSH stderr Buffer

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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C++

#include <CkSsh.h>

void ChilkatSample(void)
    {
    bool 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.

    CkSsh ssh;

    int sshPort = 22;
    success = ssh.Connect("ssh.example.com",sshPort);
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        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.
    const char *password = "mySshPassword";

    success = ssh.AuthenticatePw("mySshLogin",password);
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

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

    int channelNum = ssh.OpenSessionChannel();
    if (channelNum < 0) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    //  Run a command that writes to both stdout and stderr.
    success = ssh.SendReqExec(channelNum,"ls /etc/hosts /no/such/path");
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        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.
    ssh.put_ReadTimeoutMs(15000);

    success = ssh.ChannelReceiveToClose(channelNum);
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    const char *stdoutText = ssh.getReceivedText(channelNum,"utf-8");
    if (ssh.get_LastMethodSuccess() == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "STDOUT: " << stdoutText << "\r\n";

    const char *stderrText = ssh.getReceivedStderrText(channelNum,"utf-8");
    if (ssh.get_LastMethodSuccess() == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "STDERR: " << stderrText << "\r\n";

    ssh.Disconnect();
    }