Upstart was an event-based replacement for the traditional

init In Unix-based computer operating systems, init (short for ''initialization'') is the first process started during booting of the computer system. Init is a daemon process that continues running until the system is shut down. It is the direc ...

daemon—the method by which several

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...

computer

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

s perform tasks when the computer is started. It was written by

Scott James Remnant Scott James Remnant (born 18 July 1980) is an open source software engineer. Scott served as a long-time Debian developer until 2006 and worked as "Ubuntu Developer Manager" on the Ubuntu Linux distribution at Canonical Ltd. He now works at Goog ...

, a former employee of

Canonical Ltd. Canonical Ltd. is a UK-based privately held computer software company founded and funded by South African entrepreneur Mark Shuttleworth to market commercial support and related services for Ubuntu and related projects. Canonical employs staff ...

In 2014, Upstart was placed in maintenance mode, and other init daemons, such as

systemd systemd is a software suite that provides an array of system components for Linux operating systems. Its main aim is to unify service configuration and behavior across Linux distributions; Its primary component is a "system and service manag ...

, were recommended in place of Upstart.

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moved away from Upstart with the release of version 15.04 (''Vivid Vervet'') in favor of migrating to systemd. As of January 2022, there have been no updates released for Upstart since September 2014.

Rationale

The traditional init process was originally only responsible for bringing the computer into a normal running state after power-on, or gracefully shutting down services prior to shutdown. As a result, the design is strictly

synchronous Synchronization is the coordination of events to operate a system in unison. For example, the conductor of an orchestra keeps the orchestra synchronized or ''in time''. Systems that operate with all parts in synchrony are said to be synchronou ...

, blocking future tasks until the current one has completed. Its tasks must also be defined in advance, as they are limited to this prep or cleanup function. This leaves it unable to handle various non-startup-tasks on a modern

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elegantly, including: * The addition or removal of

USB flash drive Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply ( interfacing) between computers, peripherals and other computers. A bro ...

s and other portable storage or network devices while the machine is running * The discovery and scanning of new storage devices, especially when a disk may not even power on until it is scanned * The loading of

firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide h ...

for a device, which may need to occur after it is detected but before it is usable Upstart's event-driven model allows it to respond to events asynchronously as they are generated.

Design

Upstart operates asynchronously; it handles starting of the tasks and services during boot and stopping them during shutdown, and also supervises the tasks and services while the system is running. Easy transition and perfect

backward compatibility Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especiall ...

with

sysvinit In Unix-based computer operating systems, init (short for ''initialization'') is the first process started during booting of the computer system. Init is a daemon process that continues running until the system is shut down. It is the direct ...

were the explicit design goals; accordingly, Upstart can run unmodified sysvinit scripts. In this way it differs from most other init replacements (beside

and OpenRC), which usually assume and require complete transition to run properly, and do not support a mixed environment of traditional and new startup methods. Upstart allows for extensions to its event model through the use of initctl to input custom, single events, or event bridges to integrate many or more-complicated events. By default, Upstart includes bridges for socket, dbus, udev, file, and dconf events; additionally, more bridges are possible.

Adoption

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s and other operating systems based on the

Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ...

which use Upstart as the default init system: * Upstart is used in

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and ChromiumOS. Linux distributions that support or have supported Upstart to some extent, but moved away since or no longer use it as their default init system: *

Debian Debian (), also known as Debian GNU/Linux, is a Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of De ...

decided that systemd will be the default init system beginning with the '' Jessie'' release, after considering switching to Upstart. It was eventually removed from the Debian archives in December 2015. * Upstart was first included in

in the Ubuntu 6.10 "Edgy Eft" release in late 2006, replacing

. Ubuntu 9.10 "Karmic Koala" introduced native Upstart bootup as of Alpha 6. In turn, after the Debian project decided to adopt

on a future release in 2014,

Mark Shuttleworth Mark Richard Shuttleworth (born 18 September 1973) is a South African and British entrepreneur who is the founder and CEO of Canonical, the company behind the development of the Linux-based Ubuntu operating system. In 2002, Shuttleworth became ...

announced that Ubuntu would begin plans to migrate to systemd itself to maintain consistency with upstream. Ubuntu finished the switch to systemd as its default init system in version 15.04 (Vivid Vervet), with the exception of Ubuntu Touch. * In

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9, Upstart replaced sysvinit, however, systemd replaced Upstart in the Fedora 15 release. * Red Hat includes Upstart in their

Red Hat Enterprise Linux Red Hat Enterprise Linux (RHEL) is a commercial open-source Linux distribution developed by Red Hat for the commercial market. Red Hat Enterprise Linux is released in server versions for x86-64, Power ISA, ARM64, and IBM Z and a desktop ...

6 release. As a result, it is also used by RHEL 6 variants such as

CentOS CentOS (, from Community Enterprise Operating System; also known as CentOS Linux) is a Linux distribution that provides a free and open-source community-supported computing platform, functionally compatible with its upstream source, Red Hat En ...

Scientific Linux Scientific Linux (SL) was a Linux distribution produced by Fermilab, CERN, DESY and by ETH Zurich. It is a free and open-source operating system based on Red Hat Enterprise Linux. This product is derived from the free and open-source software ma ...

, and

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. For RHEL 7, systemd is used instead. *

openSUSE openSUSE () is a free and open source RPM-based Linux distribution developed by the openSUSE project. The initial release of the community project was a beta version of SUSE Linux 10.0. Additionally the project creates a variety of tools, s ...

included Upstart in version 11.3 Milestone 4, but not as default. systemd replaced Upstart, as the default init system in openSUSE 12.1. * Upstart is used in HP's

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for the

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(both before Palm was bought out by HP),

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, and

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smart phones, along with the HP TouchPad

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. * Upstart replaced the sysvinit in

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5 for

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Internet tablets. The latest release was version 1.13 on July 11, 2014. Since December 2018 the project website says that Upstart is in maintenance mode only, and recommends other init system, like

Rationale

Design

Adoption

See also

References

External links