Rust

Send EOF on an SSH Channel

Demonstrates the Chilkat Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel. The only argument is the channel number. EOF closes only the client-to-server direction; the application may still receive stdout, stderr, exit status, EOF, and CLOSE from the server.

Background: Many remote commands read standard input until it ends — wc, sort, cat and friends. Sending EOF is the SSH equivalent of pressing Ctrl+D: it tells the remote process no more input is coming so it can finish and emit results. After sending EOF, do not send more data on that channel; a later send may return true even though nothing is delivered.

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Rust


// Demonstrates the Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel.  The
// only argument is the channel number.  EOF closes only the client-to-server direction; output
// may still be received from the server.

let ssh = chilkat::Ssh::new();

let ssh_port = 22;
if ssh.connect("ssh.example.com", ssh_port).is_err() {
    println!("{}", ssh.last_error_text());
    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.
let password = "mySshPassword".to_string();

if ssh.authenticate_pw("mySshLogin", &password).is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

let channel_num = ssh.open_session_channel();
if channel_num < 0 {
    println!("{}", ssh.last_error_text());
    return;
}

if ssh.send_req_exec(channel_num, "wc -l").is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

// Send input to the remote command.
if ssh.channel_send_string(channel_num, "line one\nline two\nline three\n", "utf-8").is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

// Signal that no more input will be sent.  Do not send more data on this channel afterward.
if ssh.channel_send_eof(channel_num).is_err() {
    println!("{}", ssh.last_error_text());
    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.set_read_timeout_ms(15000);

// Output can still be received after EOF is sent.
if ssh.channel_receive_to_close(channel_num).is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

let Ok(output) = ssh.get_received_text(channel_num, "utf-8") else {
    println!("{}", ssh.last_error_text());
    return;
};

println!("{}", output);

ssh.disconnect();