This is a poorly phased question without any real details. What kind of system? Linux? Windows? BSD? Amiga? OS2? Generally people use ssh for Linux systems and

This is a poorly phased question without any real details. What kind of system? Linux? Windows? BSD? Amiga? OS2? Generally people use ssh for Linux systems and RDP for Windows. But your question lacks so much detail, I have to assume with Linux you want command line only and with windows you want a gui.