Rust

SSH Remote Shell with Multiple Commands

Demonstrates running several commands one after another in a single remote shell session, retrieving each command's output separately. No PTY is requested, so each command is followed by an echoed marker that signals where its output ends.

Background: Interleaving commands and reads in one shell requires a way to know where each command's output stops. An interactive session would use the shell prompt, but without a PTY the shell is non-interactive and never prints one — so the dependable technique is to append echo SOME_MARKER to each command and read up to that marker. Retrieving the text also clears the receive buffer, which matters here: if a marker were left buffered, the next receive would match it immediately and return the wrong output.

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

// Demonstrates running several commands one after another in a single remote shell session,
// retrieving each command's output separately.
// 
// No PTY is requested, so the shell runs non-interactively and never prints a command prompt.
// Because there is no prompt to synchronize on, each command is followed by an "echo" of a
// unique marker, and the output is read up to that marker.

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

let hostname = "ssh.example.com".to_string();
let port = 22;
if ssh.connect(&hostname, 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;
}

// Start a shell WITHOUT requesting a PTY.  Without a PTY the shell sees it is connected to a
// raw data pipe and enters non-interactive mode: it suppresses the command prompt, does not
// echo typed commands back, and skips interactive login scripts.  The output is therefore
// clean and easily parseable -- but because no prompt is ever sent, code must not wait for
// one.  Instead, have each command print a predictable marker, or wait for EOF / channel close.
if ssh.send_req_shell(channel_num).is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

// IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
// which means no limit -- without it, this call waits forever if the received data never
// contains a match.
ssh.set_read_timeout_ms(15000);

let case_sensitive = true;

// ---- 1st command: change directory ----
if ssh.channel_send_string(channel_num, "cd /tmp; echo END_OF_CMD_1\n", "utf-8").is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

if ssh.channel_receive_until_match(channel_num, "END_OF_CMD_1", "utf-8", case_sensitive).is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

// Retrieving the text also clears the receive buffer, which matters: if the next marker were
// left in the buffer, the following receive would match immediately.
let Ok(mut cmd_output) = ssh.get_received_text(channel_num, "utf-8") else {
    println!("{}", ssh.last_error_text());
    return;
};

println!("{}", cmd_output);

// ---- 2nd command: directory listing ----
if ssh.channel_send_string(channel_num, "ls; echo END_OF_CMD_2\n", "utf-8").is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

if ssh.channel_receive_until_match(channel_num, "END_OF_CMD_2", "utf-8", case_sensitive).is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

cmd_output = ssh.get_received_text(channel_num, "utf-8").unwrap_or_default();
if !ssh.last_method_success() {
    println!("{}", ssh.last_error_text());
    return;
}

println!("{}", cmd_output);

// ---- 3rd command: long listing, then finish the session ----
if ssh.channel_send_string(channel_num, "ls -l\n", "utf-8").is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

// No more input will be sent.
if ssh.channel_send_eof(channel_num).is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

if ssh.channel_receive_to_close(channel_num).is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

cmd_output = ssh.get_received_text(channel_num, "utf-8").unwrap_or_default();
if !ssh.last_method_success() {
    println!("{}", ssh.last_error_text());
    return;
}

println!("{}", cmd_output);

ssh.disconnect();