Background process

from Wikipedia, the free encyclopedia

In IT, processes are referred to as background processes - or background services - which do not work directly with the user , but only work in the background and thus concurrently (or asynchronously ) with the user interface . The user action mostly takes place through auxiliary processes, especially application programs that the user operates.

Background processes run asynchronously to the operating system shell . Modern Unix shells are able to start any process as a background process.

Background processes under Unix

Under Unix and its derivatives , a process can be started in a shell in the background by appending an ampersand ( & ) to the call :

cp -r /grosses/verzeichnis /ziel/verzeichnis &

With such a call, modern shells usually output the process ID of the started process. With the kill command, the background process can be terminated or controlled by signals if necessary .

Typical programs that are designed to operate as a background process are daemons .

When trying to read data from the terminal , a background process is stopped by a signal . In general, background processes should not make use of terminal input.

The shell command bg lets a process that was previously interrupted (for example with Strg+ Z) continue to run in the background. The fg command brings a background process to the foreground.

Other operating systems

In Microsoft's Windows , such applications are generally called (background) service or (in particular) Windows system service .