SysVinit is the init system of Unix - Operating system System V . A replica of this is used in some Linux distributions as the standard init system.
SysVinit is the process that is started first by the kernel and is therefore given process ID 1. This first process starts all required system services based on the desired runlevels .
SysVinit always starts the processes in a predefined order and usually only starts a process when the previous process has been completely initialized. This makes it very slow compared to other (“parallel”) init systems. On the other hand, problems can be diagnosed well.
As the first Unix, Solaris relied on a successor system, the Service Management Facility (SMF), from autumn 2004 , which is started by init and then starts, monitors and restarts services in parallel using a calculated dependency graph. The init program starts and only monitors the svc.startd process .
In the macOS operating system , launchd was introduced in April 2005 with Mac OS X Tiger (version 10.4), an alternative to SysVinit.
Many Linux distributions now have init systems that allow services to be started in parallel. This is partly done as a modification or extension of the “ GNU System-V style init ”, or as a complete replacement such as OpenRC and / or runit (for BSD or Linux, such as Gentoo Linux ). Portings of SMF (developed by Sun) and launchd (developed by Apple) were also considered, but since Linux does not have the “ Contract File System ” required for SMF and launchd is also deeply integrated into the macOS operating system, these would only be with greater effort was possible. However, these two systems were the inspiration for the similar init systems Upstart (developed by Canonical) at Ubuntu from 2006 and the more recent systemd (developed by Red Hat ) from 2010 at Fedora . Other distributions adopted it, such as Chromium OS Upstart and openSUSE systemd. By 2014, systemd prevailed in almost all Linux distributions. Canonical was therefore forced to replace Upstart with systemd in Ubuntu; The further development of Upstart has now been stopped. Since some Linux distributions no longer function without systemd, there was even Abgespaltungen ( english Forks ), for example. B. with Devuan , a Debian without systemd, or Artix Linux , an Arch Linux based on Manjaro Linux without systemd. Other Linux distributions, such as Gentoo Linux, still offer a choice of several compatible init systems.
- ↑ Tim Schürmann: System start with Systemd under Linux. Turbo booster. In: IT administrator, issue 10/2014. Heinemann Verlag, October 6, 2014, accessed on January 6, 2020 : “Systemd uses some clever concepts to massively accelerate the system start. The main inspiration was "launchd" from Mac OS X and the Service Management Facility (SMF) used by Sun Solaris. "
- ↑ a b Thorsten Leemhuis: Upstart goodbye: Linux distribution Ubuntu changes to Systemd. In: Heise online . February 14, 2014 . Retrieved April 25, 2020 .; Quote: “With Debian and Ubuntu, two of the last major Linux distributions are swiveling to Systemd, because Fedora, Arch Linux, OpenSuse or Mageia have been using Systemd for a while; Red Hat Enterprise Linux (RHEL) and Suse Linux Enterprise (SLE) are upgrading with the next major revisions, which should appear later this year. "
- ↑ Tim Schürmann: Systemd-Journal should take over the logging in Debian by default. In: Heise online . February 7, 2020 . Retrieved April 25, 2020.
- ↑ Oliver Diedrich: Unix veterans collect for Debian without Systemd. In: Heise online . November 28, 2014 . Retrieved April 25, 2020.
- ↑ Oliver Diedrich: Devuan: Let's start now. In: Heise online . January 13, 2015 . Retrieved April 25, 2020.