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.

As of 2016, most major Linux distributions continue to use systemd and the sky has not yet fallen in.

Controversy regarding systemd adoption

• Systemd runs as PID 1. It means that if a part of it crashes the whole system goes down.
• Systemd flies in the face of the Unix philosophy: "do one thing and do it well," representing a complex collection of dozens of tightly coupled binaries. Its responsibilities grossly exceed that of an init system, as it goes on to handle power management, device management, mount points, cron, disk encryption, socket API/inetd, syslog, network configuration, login/session management, readahead, GPT partition discovery, container registration, hostname/locale/time management, mDNS/DNS-SD, the Linux console and other things all wrapped into one. The agenda for systemd is to be an ever-growing and invasive middleware for GNU/Linux.
• logs are stored in binary format and are subjected to corruption. A secondary logger is needed to generate journals in readable format.
• Systemd is not portable. It need GlibC and the Linux kernel.
• Some optional dependencies like udev or dbus are now merged into the systemd code, making it more and more bloated.
• Poettering

Nonetheless, more and more distribution have started to ship it as default init because it removes the complexity of all the init scripts and exposes a set of api to system admins and distro developers.

External links

• Init systems comparison: part 1 and part 2
• [Arguments against systemd](ttp://without-systemd.org/wiki/index.php/Arguments_against_systemd)
• [Why systemd sucks](http://suckless.org/sucks/systemd)