Rust

Multiple SendReqExec on the Same Connection

Demonstrates running a series of commands on one SSH connection using SendReqExec. Each exec request requires its own logical channel — this is not a separate SSH connection, just a new session channel on the existing one.

Background: An SSH session channel is single-use for an exec request: once the command runs and the server closes the channel, that channel cannot be reused. Opening a fresh channel per command is cheap, since the expensive work — the TCP connection, key exchange, and authentication — is done once and shared. This is why running ten commands over one connection is far faster than connecting ten times.

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

// Demonstrates running a series of commands on one SSH connection using SendReqExec.  Each exec
// request requires its own logical channel.  This is not a new SSH connection -- it is simply a
// new session channel on the existing one.

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;
}

// 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);

// ---- 1st command, on its own session channel ----
let mut channel_num = ssh.open_session_channel();
if channel_num < 0 {
    println!("{}", ssh.last_error_text());
    return;
}

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

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

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

println!("{}", cmd_output);
println!("----");

// ---- 2nd command, on a NEW session channel over the same connection ----
channel_num = ssh.open_session_channel();
if channel_num < 0 {
    println!("{}", ssh.last_error_text());
    return;
}

if ssh.send_req_exec(channel_num, "nslookup chilkatsoft.com").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();