Running multiple commands in one SSH session

Question

I need to run multiple commands in a single ssh session:

// Define the client configuration
config := &ssh.ClientConfig{
    User: USERNAME,
    Auth: []ssh.AuthMethod{
        ssh.PublicKeys(pem),
    },
}

// Connect to the machine
 client, err := ssh.Dial("tcp", HOSTNAME + ":" + PORT, config)
 if err != nil {
    panic("Failed to dial: " + err.Error())
}

// Create a session
session, err := client.NewSession()
if err != nil {
    panic("Failed to create session: " + err.Error())
}
defer session.Close()

// Start running commands!
var output bytes.Buffer
session.Stdout = &output

// 1)  Login to swarm registry
fmt.Println("Logging into swarm registry...")
if err := session.Run("docker login ..."); err != nil {
    panic("Failed to login to swarm registry: " + err.Error())
}
fmt.Println(output.String())

// 2)  List all of the docker processes
fmt.Println("List swarm processes...")
if err := session.Run("docker ps"); err != nil {    // <-------- FAILS HERE
    panic("Failed to list swarm processes: " + err.Error())
}
fmt.Println(output.String())

I read through the source file (session.go) and for the Session.Run command and it says:

A Session only accepts one call to Run, Start, Shell, Output, or CombinedOutput.

For my use case I need to issue the first command to log the session in, and then issue subsequent commands once I am logged in.

Is there an alternate way to run multiple commands using the same ssh session?

have you tried screen tecmint.com/screen-command-examples-to-manage-linux-terminals — Xenwar
– Xenwar, Commented Nov 18, 2016 at 18:57
The only way to execute multiple commands in a single session is to execute them together in a shell script, or interactively by parsing the shell output and writing to the input. This is the same as if you were using ssh on the command line. — Mr_Pink
– Mr_Pink, Commented Nov 18, 2016 at 19:02
@Tyler: interactively using the remote shell isn't really advised, it's more of a last resort option, and one usually uses something like "expect" for that. As for sending a series of commands in a script, what example do you need? You have it implemented here already, just send the text to be interpreted by the remote shell (remember, ssh is just a remote "secure shell", not a general RPC system) — Mr_Pink
– Mr_Pink, Commented Nov 18, 2016 at 19:16

Tyler · Accepted Answer · 2016-11-18 20:48:11Z

3

Thanks to @JimB I am now doing this instead:

// Create a single command that is semicolon seperated
commands := []string{
    "docker login",
    "docker ps",
}
command := strings.Join(commands, "; ")

And then running it the same as before:

if err := session.Run(command); err != nil {
    panic("Failed to run command: " + command + "\nBecause: " + err.Error())
}
fmt.Println(output.String())

answered Nov 18, 2016 at 20:48

Tyler

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