Multi-user

A multi-user or multi-user system is an operating system that has the ability to provide work environments for different users and to be able to distinguish from each other.

History

The idea to let multiple users work with a computer that has been available since the early days of mainframe computers, where many IT support needs had to share a few resources. The computers used to be mainly in universities and a few large farms in use. For their service terminals, which were consisted of only a keyboard and a screen and connected to the main computer were used.

For the amortization of the high cost of unused computation times were rented out to other interested parties, for example to companies to carry out their accounting system or product development. So it could happen that the data processing of a competitor ran on the same computer. Therefore, it was necessary, the data sets of different users to shield against each other.

The provision of the disk and starting this "jobs" was carried out by service personnel, so that administrators were unable to pursue their own individual tasks. To prevent incorrect operation, such personnel received only limited access rights.

For the development of the first multi-user systems, see Time - Sharing ( computer science ).

When the first microcomputers were available, semiconductor memory was very expensive, according to just these were therefore equipped. To save disk space, available for microcomputer operating systems have been reduced to the most necessary. This time its widespread DOS is therefore not a multi-user system, as is the building on MS- DOS Windows 3.x and 9x systems from Microsoft.

Rights management

The multi-user ability of an operating system is achieved by a set of individual measures. This includes for example the management of private working directories and personal preferences for each user. On multi-user systems, users expect a concept for the management of access rights to stored data, and other system resources.

Multisession

The term multi-user is not necessarily simultaneous work from. Historically there have been quite some computers where different users one by one, but could not work the same in their own work environments. If multitasking was provided, at least could have multiple tasks simultaneously perform a user. Simultaneously if different users are own work environments are available, it is called a multisession.

Systems that are not only multi -user capable, but also capable of multitasking, need a storage protection concept in general. In current computer systems, one usually works this virtual locations in the main memory, the (integrated as a separate module on the motherboard or directly in the processor ) with hardware support by MMU are process- or user- specific configuration.

Multi-user systems in networks

Some multi-user systems also allow the application via computer networks such as the Internet. Thus, many different users all over the world can connect over the Internet to the computer, log on and work simultaneously on the same machine. This solution was created primarily for cost reasons, because sooner were single computer very expensive. Today, this approach is rather rare to find. The console (command prompt, Unix Shell) Linux or Unix systems is, however, still referred to as " terminal ".

Safety aspects

The privilege system of a multi-user system protects the user mainly before Ausspähversuchen other users and data loss due to accidental deletion of files. However, the biggest advantage is thereby secured preservation of system integrity in operation without administration rights. A malicious program can only spread as far as the user's write permissions rich. A system-wide dissemination, compromise the kernel or basic system services, and thus automatic activation at startup are thus possible only by exploiting special attack vectors such as setuid or application vulnerabilities.

User Switching

• See runas, sudo, su

Examples

• Unix
• Linux
• Apple MacOS from 1992
• Microsoft Windows NT (only limited Usable Depending on the edition, version, and license. )

Multi-user systems outside of operating systems

Multi-user systems can not only be operating systems in a broad sense, but all application systems that can operate for more than one user. To this end, they must also ( in addition to the operating system) can handle the activities of multiple users separated from each other and to certain technical requirements ( inter alia protection against simultaneously changing the same data ) offer.

Contrary, single-user system.

Examples:

• Applications for graphics or text editing are typically Einbenutzersysteme; to the result file (simultaneously), only one creator work.
• A ticket ordering system is a multi-user system when orders can be processed simultaneously by multiple users.
• Tools for project management can Einbenutzersysteme (eg to create a schedule ). If multiple users can, for example, to report back their results at the same time, there are multi-user systems.

• Operating system theory
• User Management