编辑“︁Systemd”︁

{{NoteTA 
|T = systemd 
|G1 = IT 
|1 = library ; zh-hans : 函数库 ; zh-cn : 函数库 ; zh-hant : 函式庫 ; zh-tw : 函式庫 ; zh-hk : 函數庫 ; zh-mo : 函數庫
|2 = daemon ; zh-hans : 守护进程 ; zh-cn : 守护进程 ; zh-hant : 常駐程式 ; zh-tw: 常駐程式 ; zh-hk : 常駐程式 ; zh-mo : 常駐程式
}}
<!--{{lowercase}}-->
{{Infobox software
| name = systemd
| title = systemd
| author = {{Tsl|en|Lennart Poettering}}, {{Tsl|en|Kay Sievers}}, {{Tsl|en|Harald Hoyer}}, Daniel Mack, Tom Gundersen and David Herrmann
| developer = Lennart Poettering, Kay Sievers, Harald Hoyer, Daniel Mack, Tom Gundersen, David Herrmann等人
| logo = Systemd-logo.svg
| screenshot = Systemd-on-fedora.svg
| caption = 使用systemd的Fedora 17启动信息
| released = {{Start date|2010|03|30|df=yes}}
| latest_release_version = 252
| latest_release_date = {{Release date and age|2022|10|31|br=yes}}
| programming_language = [[C语言|C]]
| operating_system = [[Linux]]
| platform = 
| language = 
| genre = [[系統軟件]]
| license = [[GNU宽通用公共许可证|GNU LGPL]] 2.1+<ref name="license" />
| website = {{URL|https://systemd.io}}
}}

'''systemd'''是[[Linux]]電腦[[作業系統]]之下的一套[[init|中央化系統及設定管理程式]]（init），包括有[[守护进程]]、[[函式庫]]以及應用軟體，由{{Tsl|en|Lennart Poettering}}带头开发。其开发目标是提供更优秀的[[軟體框架|框架]]以表示{{Tsl|en|Service (systems architecture)|服务 (系统结构)|系统服务}}间的依赖关系，并依此实现系统初始化时服务的并行启动，同时达到降低[[Shell]]的{{Tsl|en|Computational overhead|系统开销}}的效果，最终代替现在常用的[[System V]]与[[BSD]]风格init程序。

目前絕大多數的[[Linux發行版]]都已採用systemd代替原來的[[UNIX System V|System V]]。

systemd在[[LGPL]] 2.1及其后续版本许可证下开源发布<ref name="license">{{citation |url=http://0pointer.de/blog/projects/systemd-update-3.html |title=systemd Status Update |author=Lennart Poettering |accessdate=2012-04-28 |date=2012-04-21 |archive-date=2015-08-27 |archive-url=https://web.archive.org/web/20150827082932/http://0pointer.de/blog/projects/systemd-update-3.html |dead-url=no }}</ref><ref>{{citation |url=http://0pointer.de/blog/projects/systemd.html#faqs |publisher=0pointer |work=systemd |title=FAQs |author=Lennart Poettering |accessdate=2011-06-16 |archive-date=2017-01-15 |archive-url=https://web.archive.org/web/20170115175026/http://0pointer.de/blog/projects/systemd.html#faqs |dead-url=no }}</ref>。

== 起源 ==
systemd这一名字源于[[Unix]]中的一个惯例：在Unix中常以“d”作为系统[[守护进程]]（{{langx|en|'''d'''aemon}}，亦称[[后台进程]]）的后缀标识。除此以外，systemd亦是借代英文术语[[系统D]]，而这一术语即是用于描述一个人具有快速地适应环境并解决困难的能力<ref name=control-center>{{citation |url = http://www.h-online.com/open/features/Control-Centre-The-systemd-Linux-init-system-1565543.html |title = Control Centre: The systemd Linux init system |authors = Lennart Poettering, Kay Sievers, Thorsten Leemhuis |date = 2012-05-08 |accessdate = 2012-06-10 |archive-date = 2012-06-14 |archive-url = https://web.archive.org/web/20120614092143/http://www.h-online.com/open/features/Control-Centre-The-systemd-Linux-init-system-1565543.html |dead-url = no }}</ref>。

== 设计 ==
[[File:Systemd components.svg|thumb|320px|systemd組件]]
[[File:Linux kernel unified hierarchy cgroups and systemd.svg|thumb|320px|專門由systemd所使用的統一層次結構[[控制組]]]]

与[[UNIX System V|System V]]风格init相比，systemd采用了以下新技术：
* 將service（服務）、target（執行模式，類似於[[運行級別]]）、mount、timer、snapshot、path、socket、swap等稱為Unit。比如，一個auditd服務（就是auditd.service）就是一個Unit，一個multi-user.target執行模式也是一個Unit。
* 采用[[Socket]]激活式与[[D-Bus]]激活式服务，以提高相互依赖的各服务的并行运行性能；
* 用[[cgroups]]代替[[进程ID]]来追踪进程，因此即使是两次[[Fork (操作系统)|fork]]之后生成的常駐程式也不会脱离systemd的控制。
* 用target代替System V的[[運行級別]]（Runlevel），比如，SystemD的graphical.target相當於System V的init 5，multi-user.target相當於System V的init 3。
* 內建journald [[日誌]]管理系統。
* 內建resolved、timesyncd、networkd等元件。
* 引入<tt>localectl</tt>、<tt>timedatectl</tt>、<tt>hostnamectl</tt>等新命令，系統配置更方便。

从设计构思上说，由于systemd使用了cgroup与fanotify等组件以实现其特性，所以只适用于Linux<ref>{{citation |url=http://0pointer.de/blog/projects/systemd.html |title=systemd FAQ |author=Lennart Poettering |date=2010-04-30 |accessdate=2011-12-14 |archive-date=2017-01-15 |archive-url=https://web.archive.org/web/20170115175026/http://0pointer.de/blog/projects/systemd.html |dead-url=no }}</ref>。有鉴于此，考虑到[[Debian GNU/kFreeBSD|kFreeBSD]]分支的软件源无法纳入systemd，为与其他分支保持一致，[[Debian]]开发者尽力避免纳入systemd<ref>{{citation |url=http://lwn.net/Articles/452865/ |title=Debian debates systemd |author=Jake Edge |date=2011-07-27 |accessdate=2011-12-14 |archive-date=2012-05-15 |archive-url=https://web.archive.org/web/20120515140912/http://lwn.net/Articles/452865/ |dead-url=no }}</ref>。但Lennart Poettering本人对此并不在意，并称「Debian GNU/kFreeBSD不过是玩具系统」<ref>{{citation |url=http://linuxfr.org/nodes/86687/comments/1249943 |title=Un entretien avec Lennart Poettering) |date=2011-07-05 |accessdate=2011-12-14 |archive-date=2014-08-05 |archive-url=https://web.archive.org/web/20140805082959/http://linuxfr.org/nodes/86687/comments/1249943 |dead-url=no }}</ref>。但Debian 8.0 Jessie開始以systemd取代sysvinit。<ref>{{citation |url=http://www.theregister.co.uk/2015/04/27/debian_quits_wheezing_ships_jessie/ |title=Debian ships new 'Jessie' release with systemd AND sysvinit |author=Richard Chirgwin |date=2015-04-27 |accessdate=2016-05-23 |archive-date=2016-04-25 |archive-url=https://web.archive.org/web/20160425231722/http://www.theregister.co.uk/2015/04/27/debian_quits_wheezing_ships_jessie |dead-url=no }}</ref>。

== 应用 ==
systemd已纳入众多[[Linux发行版]]的软件源中，以下简表：

; 默认init程序为systemd的发行版
* [[Fedora (作業系統)|Fedora]] 15及后续版本<ref>{{citation |author=Dj Walker-Morgan |title=Fedora 15's Lovelock released |publisher=The H |url=http://h-online.com/-1249820 |date=2011-05-24 |accessdate=2011-05-26 |deadurl=yes |archiveurl=https://archive.today/20120712235613/http://h-online.com/-1249820 |archivedate=2012-07-12 }}</ref>{{notetag|原先Fedora开发者打算在Fedora 14发布的时候便将systemd设为默认init程序，但最后还是推迟到Fedora 15才实行<ref>{{citation |url=http://lwn.net/Articles/401856/ |title=systemd and Fedora 14 |author=Jake Edge |publisher=LWN |date=2010-08-25 |accessdate=2011-02-03 |archive-date=2010-12-27 |archive-url=https://web.archive.org/web/20101227140146/http://lwn.net/Articles/401856/ |dead-url=no }}</ref>。}}
* [[CentOS]] 7及後續版本。
* [[Mageia]] 2<ref>{{citation |url=http://h-online.com/-1582479 |title=Mageia 2 arrives with GNOME 3 and systemd |author=Fabian Scherschel |publisher=The H |date=2012-05-23 |accessdate=2012-05-26 |deadurl=yes |archiveurl=https://web.archive.org/web/20131208100442/http://www.h-online.com/open/news/item/Mageia-2-arrives-with-GNOME-3-and-systemd-1582479.html |archivedate=2013-12-08 }}</ref>
* [[Mandriva Linux|Mandriva]] 2011<ref>{{citation |url=http://h-online.com/-1332627 |title=Mandriva 2011 arrives with systemd |author=Dj Walker-Morgan |publisher=The H |date=2011-08-29 |accessdate=2011-08-29 |deadurl=yes |archiveurl=https://archive.today/20120709025015/http://h-online.com/-1332627 |archivedate=2012-07-09 }}</ref>
* [[openSUSE]] 12.1 及后续版本<ref>{{citation |url=http://h-online.com/-1380033 |title=openSUSE 12.1 arrives with systemd and Btrfs |author=Chris von Eitzen |publisher=The H |date=2011-11-16 |accessdate=2011-11-16 |deadurl=yes |archiveurl=https://web.archive.org/web/20120420063250/http://www.h-online.com/open/news/item/openSUSE-12-1-arrives-with-systemd-and-Btrfs-1380033.html |archivedate=2012-04-20 }}</ref>
* [[Red Hat Enterprise Linux]] 7及后续版本，包括其衍生品[[CentOS]]、[[Scientific Linux]]、[[Oracle Linux]]等
* [[Arch Linux]]在2012年10月13日将systemd-sysvcompat纳入base软件组，自此Arch Linux默認安裝完即以systemd為init程序<ref>{{cite web | url=https://www.archlinux.org/news/systemd-is-now-the-default-on-new-installations/ | title=systemd is now the default on new installations | publisher=Arch Linux Official | accessdate=2012-10-16 | author=Bächler, Thomas | archive-date=2012-10-15 | archive-url=https://web.archive.org/web/20121015231822/http://www.archlinux.org/news/systemd-is-now-the-default-on-new-installations/ | dead-url=no }}</ref>，同时也提供了与Arch自带启动脚本兼容用的systemd启动脚本包以方便用户，使用户能“开箱即用”<ref>{{citation |url=https://wiki.archlinux.org/index.php/Systemd |publisher=Archlinux Wiki |title=systemd |accessdate=2011-03-09 |archive-date=2011-05-23 |archive-url=https://web.archive.org/web/20110523104755/https://wiki.archlinux.org/index.php/Systemd |dead-url=no }}</ref>
* [[Chakra GNU/Linux]]，在2012.10的光碟映像檔發佈後預設使用systemd。<ref>{{citation |url=http://chakra-project.org/news/index.php?/archives/11-Full-switch-to-Systemd-with-Claire-2012.10-ISO-released-today.html |publisher= |title=Full switch to Systemd with Claire-2012.10 ISO released today |accessdate=2012-10-28 |deadurl=yes |archiveurl=https://web.archive.org/web/20130315131349/http://chakra-project.org/news/index.php?%2Farchives%2F11-Full-switch-to-Systemd-with-Claire-2012.10-ISO-released-today.html |archivedate=2013-03-15 }}</ref>
* [[Debian GNU/Linux]]，在2014年的技術委員會的init系統投票中決定在Debian 8“Jessie”中以Linux為核心的版本轉換到systemd<ref>{{cite web|author=Bdale Garbee|title=The Debian technical committee vote concludes|url=http://lwn.net/Articles/585363/|publisher=LWN.net|accessdate=2014-02-12|archive-date=2014-02-22|archive-url=https://web.archive.org/web/20140222145737/http://lwn.net/Articles/585363/|dead-url=no}}</ref>。
* [[Ubuntu]] 15.04及后续版本<ref>{{citation |url=https://wiki.ubuntu.com/VividVervet/ReleaseNotes#Boot_and_service_management |title=VividVervet/ReleaseNotes |author=seb128 |publisher=Ubuntu Wiki |date=2015-04-24 |accessdate=2015-04-29 |archive-date=2015-06-11 |archive-url=https://web.archive.org/web/20150611043849/https://wiki.ubuntu.com/VividVervet/ReleaseNotes#Boot_and_service_management |dead-url=no }}</ref>

; 可以使用systemd的发行版
* [[Gentoo]]，同OpenRC一起被Gentoo官方支持<ref>{{citation |url=https://bugs.gentoo.org/show_bug.cgi?id=318365#c210 |publisher=Gentoo's Bugzilla |work=systemd – bug #318365 |title=Comment #210 |accessdate=2011-07-05 |archive-date=2015-02-16 |archive-url=https://web.archive.org/web/20150216210945/https://bugs.gentoo.org/show_bug.cgi?id=318365#c210 |dead-url=no }}</ref><ref>{{citation |url=http://www.gentoo.org/proj/en/base/systemd/ |publisher=Gentoo's Documentation |title=systemd |accessdate=2011-07-05 |archive-date=2011-06-26 |archive-url=https://web.archive.org/web/20110626121601/http://www.gentoo.org/proj/en/base/systemd/ |dead-url=no }}</ref><ref>{{citation |url=http://wiki.gentoo.org/wiki/Systemd |publisher=Gentoo wiki |title=systemd |accessdate=2012-08-26 |archive-date=2012-10-12 |archive-url=https://web.archive.org/web/20121012004106/http://wiki.gentoo.org/wiki/Systemd |dead-url=no }}</ref>

[[File:Systemd manager.png|缩略图|323x323像素|systemd-manager]]
除此以外，systemd已由Lennart Poettering提请纳入[[GNOME]] 3.2的外部依赖关系列表<ref>{{citation |url=http://mail.gnome.org/archives/desktop-devel-list/2011-May/msg00427.html |title=systemd as an external dependency |author=Lennart Poettering |publisher=GNOME |work=desktop-devel mailing list |date=2011-05-18 |accessdate=2011-05-26 |archive-date=2014-10-10 |archive-url=https://web.archive.org/web/20141010045031/https://mail.gnome.org/archives/desktop-devel-list/2011-May/msg00427.html |dead-url=no }}</ref>，而这意味着所有使用[[GNOME]]的发行版都应该使用systemd，最低限度来说也必须将其作为配置选项之一。

== 注释 ==
{{NoteFoot}}

== 参考文献 ==
{{Reflist|33em}}

== 外部链接 ==
{{Div col|33em}}
* {{official website|http://www.freedesktop.org/wiki/Software/systemd/}}
* {{citation |url = http://0pointer.de/blog/projects/systemd.html |publisher = 0pointer |title = systemd |accessdate = 2012-06-10 |archive-date = 2017-01-15 |archive-url = https://web.archive.org/web/20170115175026/http://0pointer.de/blog/projects/systemd.html |dead-url = no }}
* {{citation |url = http://fedoraproject.org/wiki/Features/systemd |publisher = Fedora |title = systemd project |accessdate = 2012-06-10 |archive-date = 2012-05-21 |archive-url = https://web.archive.org/web/20120521095736/http://fedoraproject.org/wiki/Features/systemd |dead-url = no }}
* {{citation |url = http://lwn.net/Articles/389149/ |publisher = LWN |title = The road forward for systemd |accessdate = 2012-06-10 |archive-date = 2012-10-21 |archive-url = https://web.archive.org/web/20121021141311/http://lwn.net/Articles/389149/ |dead-url = no }}
* {{citation |url = http://cgit.freedesktop.org/systemd/ |publisher = freedesktop |title = cgit |accessdate = 2012-06-10 |archive-date = 2012-06-20 |archive-url = https://web.archive.org/web/20120620125523/http://cgit.freedesktop.org/systemd |dead-url = no }}
{{Div col end}}

== 参见 ==
{{Portal box|Linux|自由軟體}}
* [[BusyBox]]
* {{Tsl|en|launchd}}
* [[readahead]]
* {{Tsl|en|Service Management Facility|服务管理程序}}
* [[Upstart]]
* [[OpenRC]]

{{-}}
{{Unix中的服务管理}}
{{Freedesktop.org}}
{{Linux内核}}

[[Category:Unix进程和任务管理相关软件]]
[[Category:Linux文件系统相关软件]]