For other uses, see Upstart (disambiguation).
Scott James Remnant
24 August 2006
1.10 / August 23, 2013; 2 months ago (2013-08-23)
GNU General Public License
Upstart is an event-based replacement for the traditional init daemon -- the method by which several Unix-like computer operating systems perform tasks when the computer is started. It was written by Scott James Remnant, a former employee of Canonical Ltd.
4 See also,
6 External links,
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, 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 desktop computer elegantly, including:
The addition or removal of USB pen drives and other portable storage / network devices while the machine is running,
The discovery and scanning of new storage devices, without locking the system, especially when a disk may not even power on until it is scanned,
The loading of firmware 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.
Upstart operates asynchronously -- as well as handling the starting of tasks and services during boot and stopping them during shutdown, it supervises them while the system is running.
Easy transition and perfect backwards compatibility with sysvinit were explicit design goals. As such, Upstart is able to run sysvinit scripts unmodified. In this way it differs from most other init replacements, which usually assume and require complete transition to run properly, and don't support a mixed environment of traditional and new startup methods.
As Upstart matures, it is intended that its role will expand to the duties currently handled by cron, anacron, the at command's daemon (atd), and possibly (but much less likely) inetd.
Distributions in which Upstart is enabled by default:
Upstart was first included in Ubuntu in the 6.10 (Edgy Eft) release in late 2006, replacing sysvinit. Ubuntu 9.10 (Karmic Koala) introduced native Upstart bootup as of Alpha 6.,
Upstart replaced the sysvinit in Maemo 5 for Nokia Internet tablets.,
Upstart is used in HP's webOS for the Palm Pre, Palm Pixi (both before Palm was bought out by HP), HP Veer, and HP Pre 3 smart phones, along with the HP TouchPad tablet.,
Upstart is used in Google's Chrome OS.,
Distributions that used Upstart in some versions but moved to systemd in later versions:
Upstart replaced sysvinit in Fedora 9, and functioned in the same manner as it did in Ubuntu, i.e. it replaces sysvinit, while retaining the existing scripts. However, Upstart has been replaced by systemd in Fedora 15 release.,
Red Hat includes Upstart in their Red Hat Enterprise Linux 6 release. As a result, it is also used by RHEL 6 variants such as Centos, Scientific Linux, and Oracle Linux.,
Debian considered switching for the squeeze release, and is discussing it again for the jessie+1 release.,
openSUSE included upstart in version 11.3 Milestone 4, but not as default. systemd replaced Upstart, as the default init system in openSUSE 12.1.