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→GUI vs CLI: Advantages and Disadvantages
It’s important to keep information private in some contexts, and to share information in other contexts. The operating system is responsible for enforcing security rules. For example, on a smartphone, a social media app shouldn’t be able to access data from a banking app, and on a cloud server, one customer shouldn’t be able to access another customer’s data. However, multiple smartphone apps might be permitted to access a photo album, and a company employee might need to view a report generated on a server from multiple customers’ data.
The operating system is responsible for enforcing the security policyrules but not for creating them -- the system administrators and/or users are responsible for creating and maintaining the security settings and policies which the operating system enforces.
=== Hardware Abstraction ===
There are many different types of devices that perform similar functions, and multiple ways that these devices can be connected. For example:
* A keyboard may be connected via a USB connection, or a wireless Bluetooth connection, or may be created as a virtual keyboard on a touchscreen.* A mouse may be connected via a wired USB, wireless USBdongle, or wireless Bluetooth connection. But there are also other types of devices which can provide the same capability of allowing the user to interact with the display, including trackpads, trackballs, and touchscreens.
* Sound may be played over built-in speakers, an external analog speaker, an analog headset, a digital speaker or headset with a USB connection, a Bluetooth speaker, earbuds, or headset, or played through a television connected via HDMI.
The operating system also abstracts away these hardware details. This means that programs can access devices in a general way without having to be programmed to individually deal with each type of device that may be used. This enables a program to request keyboard input or play sounds without regard to the details of the specific hardware available.
=== Maintaining the Programming Model ===
=== System Libraries ===
Many programs need to perform the same operations, such as accessing the network, playing sound, or drawing something on the screen. Libraries provide a common set of software routines (also known as functions, methods, procedures, or subroutines, or functions) which programs access to perform these common operations. This eliminates the need for each program to contain duplicate code for these common operations, which reduces software duplication and program size. Although additional libraries may be installed on the computer, the system libraries provided as part of the operating system provide the most broadly-used routines required by nearly every program.
=== Services ===
=== Utilities and Applications ===
Most operating systems provide a set of tools to enable users to perform setup, configuration, and maintenance tasks. For example, they may provide “utility” software to add/remove software, configure hardware, and manage files. This utility software may take the form of commands that are accessed through a CLI, or graphical utilities that are accessed through a GUI. Most operating systems also provide a set of basic starter applications, such as a text editor, clock, a few games, and sometimes a web browser; the quantity and complexity of the included applications vary considerably from one operating system to another.
== GUI vs CLI: Advantages and Disadvantages ==
To compare the data demands of the two types of user interfaces:
* A GUI on a 1920x1080 ("full high definition") monitor displays about 6 megabytes of data (2 megapixels million pixels x 3 bytes per pixel)* A CUI TUI on an 80x25 character terminal displays about 2 kilobytes of data (0.002 megabytes) at one time
* A CLI is well-suited to automation. Edits could be applied to hundreds of pictures in a few seconds, if the edits can be adequately described on the command-line.
