Switching the user (su) seems to interrupt the connection for submitting further commands

[LorenzKahl]

I'm successfully connecting to my server using agentForwarding. My problem is that I then need to switch the user using sudo /bin/su -l deploymentUser which seems to interrupt the connection for submitting further commands.

I can run the commands in this order using iTerm without any problems:

[lkahl@myremoteserver ~]$ whoami
lkahl
[lkahl@myremoteserver ~]$ sudo /bin/su -l deploymentUser
[deploymentUser@myremoteserver ~]$ whoami
deploymentUser
[deploymentUser@myremoteserver ~]$

Here is my test-setup in my Grunt file:

        sshconfig: {
            myremoteserver: {
                host: 'myremoteserver.com',
                agent: process.env.SSH_AUTH_SOCK,
                agentForward: true,
                username: '<%= deploymentSettings.username %>',
            }
        },
        sshexec: {
            deploy: {
                command: 'whoami; sudo /bin/su -l deploymentUser; whoami',
                options: {
                    config: 'myremoteserver',
                }
            }
        },

When I run the task with --verbose this is the output I get:

Running "sshexec:deploy" (sshexec) task
Verifying property sshexec.deploy exists in config...OK
File: [no files]
Options: config="myremoteserver", host=false, username=false, password=false, agent="", agentForward=false, port=22, proxy={"port":22}, ignoreErrors=false, minimatch={}, pty={}, suppressRemoteErrors=false, callback=undefined
Raw Options: config="myremoteserver", host=false, username=false, password=false, agent="", agentForward=false, port=22, proxy={"port":22}, ignoreErrors=false, minimatch={}, pty={}, suppressRemoteErrors=false, callback=undefined
Verifying property sshconfig.myremoteserver exists in config...OK
Options: config="myremoteserver", host="myremoteserver", username="lkahl", password=false, agent="/tmp/launch-fj7pif/Listeners", agentForward, port=22, proxy={"port":22}, ignoreErrors=false, minimatch={}, pty={}, suppressRemoteErrors=false, callback=undefined
Connection :: connect
Connection :: ready
Executing :: whoami; sudo /bin/su -l deploymentUser; whoami
lkahl
[deploymentUser@myremoteserver ~]$ 

And from this point on nothing happens... so the grunt task will never finish :-(

Is there any way to have the third command (whoami) executed after the userswitch and still get the output displayed in my grunt task.

I'm not a command line hero at all – I just guess that switching the user remotely also causes the terminal-process to switch/spawn to a new instance which doesn't get forwarded properly to the process grunt listens to...

Any ideas?