Also: chvt 2 is the same as CTRL-ALT-F2
However, if you are in single user mode, neither of those will work. You can get another login, but it how depends on your distro.
Newer Ubuntu systems use "Upstart" instead of inittab. For these systems, a simple"start tty2" will do the job. After typing that, you can hold "Alt" and press F2 to login there and of course Alt-F1 will bring you back to where you started.
Centos and other systems that still use inittab require a different approach. You'd think you could just do "/sbin/mingetty tty2 &", but that won't work. Nor will "/bin/login tty2 &" or trying to start bash with input and output directed to another tty. What WILL work is sulogin: "/sbin/sulogin tty2 &". Switch to Alt-F2, give the root password and you have another terminal to work in.
It's certainly possible that another distro may require another way or may work with something that didn't work on Centos.