Interactive session - X windows (GUI: local console or remote)
Interactive session - command line (local console, or remote ssh session)
Background operation (daemons, cron jobs, no user interaction)
Command line (terminal) logins vs. X windows.
"X windows" is the standard graphical user interface for Unix.
It is used on workstation consoles, and can be redirected to remote displays.
Whether or not it
can be used depends on the capabilities of the terminal ("terminal" means
"whatever you are sitting at" - it may be a real terminal or a Mac or PC running
terminal emulation software). X servers are available for MacOS and MS Windows.
X windows is location independant - remote X windows
programs run the same as local (console).
Programs run on the UNIX machine and you see output on your terminal.
The terminal may be remote (over the network), directly wired, or be the
console device (workstations).
When you log in with a command line session, a special program called a 'shell'
is run, commands that you type are processed by the shell. Most of this class concerns the command line
interface because:
it is always available (often dial-in access is too slow for good X-windows
display)
it is scriptable and can be used to set up unattended jobs
it is basis for the underlying tools run by the GUI, and the GUI menu configurations
Certain Client-Server programs (Ex. Mathematica) can use a Mac or PC for display and
UNIX for number crunching, with a custom network protocol linking the two.
Displaying graphical output on the local console is generally faster than displaying
remotely. Some graphical applications are coded in such a way as to make remote display almost impossible.
Remote display to another Mac/UNIX/Linux workstation often works better than to a PC.
Don't confuse the User Interface with the Operating System.
X windows provides the mechanism for graphical displays, but does not mandate any particular
look and feel.
There are many different graphical interfaces based on the X-windows core libraries;
CDE, Gnome, KDE, ... .
It may even be configured to look similar to MS Windows or MacOS.
Similarly, there are various command line shells available which determine the
look and feel of the text-based interface.
