OpenSSH SSH client (remote login program)

-f      Requests ssh to go to background just before command execution.  This is useful if ssh is going to
        ask for passwords or passphrases, but the user wants it in the background.  This implies -n.  The
        recommended way to start X11 programs at a remote site is with something like ssh -f host xterm.

        If the ExitOnForwardFailure configuration option is set to “yes”, then a client started with -f
        will wait for all remote port forwards to be successfully established before placing itself in the
        background.

ssh connects and logs into the specified hostname (with optional user name).  The user must prove his/her
identity to the remote machine using one of several methods depending on the protocol version used (see
below).

If command is specified, it is executed on the remote host instead of a login shell.

-l login_name
        Specifies the user to log in as on the remote machine.  This also may be specified on a per-host
        basis in the configuration file.

-n      Redirects stdin from /dev/null (actually, prevents reading from stdin).  This must be used when ssh
        is run in the background.  A common trick is to use this to run X11 programs on a remote machine.
        For example, ssh -n shadows.cs.hut.fi emacs & will start an emacs on shadows.cs.hut.fi, and the X11
        connection will be automatically forwarded over an encrypted channel.  The ssh program will be put
        in the background.  (This does not work if ssh needs to ask for a password or passphrase; see also
        the -f option.)