Systemd

systemd is a software suite for central management and configuration of the Linux operating system. It consists of server applications (daemons), run time libraries, development tools, and command line utilities.

systemd has been used as the Linux init system to bootstrap the user space and manage all processes subsequently, replacing the UNIX System V and Berkeley Software Distribution (BSD) init systems. The name systemd adheres to the Unix convention of naming daemons by appending the letter d. The software suite is published as free and open-source software under the terms of the GNU Lesser General Public License (LGPL) version 2.1 or later. One of systemd's main goals is to unify basic Linux configurations and service behaviors across all distributions.

As of 2015, most major Linux distributions have adopted systemd as their default init system. The increasing adoption of systemd has been controversial, with critics arguing that the software has violated the Unix philosophy by becoming increasingly complex, and that distributions have been forced to adopt it due to its coupling with various other software, including most controversially, the GNOME desktop environment.