systemd

systemd is a software suite for system and service management on Linux built to unify service configuration and behavior across Linux distributions. Its main component is an init system used to bootstrap user space and manage user processes. It also provides various daemons and utilities, including device management, login management, network connection management, and event logging. The name systemd adheres to the Unix convention of naming daemons by appending the letter d, and also plays on the French phrase Système D (a person's ability to quickly adapt and improvise in the face of problems).

In Linux distributions, systemd is used as a replacement for Sysvinit and other init systems. Since 2015, nearly all Linux distributions have adopted systemd. It has been praised by developers and users of distributions that adopted it for providing a stable, fast out-of-the-box solution for issues that had existed in the Linux space for years. At the time of its adoption, it was the only parallel boot and init system offering centralized management of processes, daemons, services, and mount points..

Critics of systemd contend it suffers from feature creep and has damaged interoperability across Unix-like operating systems (as it does not run on non-Linux Unix derivatives like BSD or Solaris). In addition, they contend systemd's large feature set creates a larger attack surface. This has led to the development of several minor Linux distributions replacing systemd with other init systems like SysVinit or OpenRC.