Many ideas in UNIX were new. Other operating systems copied them. Today, there are many operating systems that have some of the ideas of UNIX in them. For this reason, some people talk about a "UNIXphilosophy" of doing things.Linux is one of these systems with many of the UNIX ideas in it. Linux does not usecode from UNIX. Linux only shares some of the ideas and the names of commands. So, Linux is not a UNIX operating system. Instead it is called "UNIX-like".
There can be many different users in a UNIX and UNIX-like operating system. Most of them have a personal area where they can put things. This is called a useraccount.
One way of using a UNIX system is with thecommand line interface. Users run commands and programs by typing text characters. This takes time to learn, but it is a very powerful and flexible way of working. It is still used by most UNIX administrators. These commands are run in ashell, which can change slightly between one system and another. A user can get to a command line interface over a network with tools likeSSH orTelnet.
Agraphical user interface (GUI) is the other method. TheX Window System is a very common GUI for UNIX systems. The X Window System is only a shell of a graphical interface. It has manyprotocols. The X Window System itself does not let the user to move and resize windows. Users need a window manager ordesktop environment to do that.
Some of the popular desktops and window managers are:
Today, there are two kinds of operating systems that are like UNIX.
The first group is all those that share some kernel code with the original from Bell Labs atAT&T. This includes the commercial UNIX types:Solaris orAIX.
The second group includes free operating systems that usually haveBSD in their name, likeFreeBSD,OpenBSD, andNetBSD. These are based onBSD.Mac OS X is also based on BSD.[1][2]
There are also free systems based on theLinuxkernel. These do not share any code with the original UNIX. BSD systems share very little code with the original UNIX because much of the code has been rewritten over many years. Many people use the termsUNIX and UNIX-like systems to be clear.
Most applications can run on any modern UNIX or UNIX-like system.[3] KDE and GNOME were developed for Linux and later changed to run on commercial types of UNIX.
