Swift

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.

Chilkat Swift Downloads

Download Chilkat for Swift

Swift


func chilkatTest() {
    var success: Bool = false

    //  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 = CkoSsh()!

    var hostname: String? = "ssh.example.com"
    var port: Int = 22
    success = ssh.connect(hostname: hostname, port: port)
    if success == false {
        print("\(ssh.lastErrorText!)")
        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.
    var password: String? = "mySshPassword"

    success = ssh.authenticatePw(login: "mySshLogin", password: password)
    if success == false {
        print("\(ssh.lastErrorText!)")
        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.readTimeoutMs = 15000

    //  ---- 1st command, on its own session channel ----
    var channelNum: Int = ssh.openSessionChannel().intValue
    if channelNum < 0 {
        print("\(ssh.lastErrorText!)")
        return
    }

    success = ssh.sendReqExec(channelNum: channelNum, command: "ls -al")
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    success = ssh.channelReceive(toClose: channelNum)
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    var cmdOutput: String? = ssh.getReceivedText(channelNum: channelNum, charset: "utf-8")
    if ssh.lastMethodSuccess == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    print("\(cmdOutput!)")
    print("----")

    //  ---- 2nd command, on a NEW session channel over the same connection ----
    channelNum = ssh.openSessionChannel().intValue
    if channelNum < 0 {
        print("\(ssh.lastErrorText!)")
        return
    }

    success = ssh.sendReqExec(channelNum: channelNum, command: "nslookup chilkatsoft.com")
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    success = ssh.channelReceive(toClose: channelNum)
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    cmdOutput = ssh.getReceivedText(channelNum: channelNum, charset: "utf-8")
    if ssh.lastMethodSuccess == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    print("\(cmdOutput!)")

    ssh.disconnect()

}