Ubuntu

Ubuntu is built on Debian's architecture and infrastructure, and comprises Linux server, desktop and discontinued phone and tablet operating system versions.[28] Ubuntu releases updated versions predictably every six months,[29] and each release receives free support for nine months (eighteen months prior to 13.04)[30] with security fixes, high-impact bug fixes and conservative, substantially beneficial low-risk bug fixes.[31] The first release was in October 2004.

Current long-term support (LTS) releases are supported for five years, and are released every two years. Since the release of Ubuntu 6.06, every fourth release receives long-term support (LTS).[29] Long-term support includes updates for new hardware, security patches and updates to the 'Ubuntu stack' (cloud computing infrastructure).[32] The first LTS releases were supported for three years on the desktop and five years on the server; since Ubuntu 12.04 LTS, desktop support for LTS releases was increased to five years as well.[33][34][35] LTS releases get regular point releases with support for new hardware and integration of all the updates published in that series to date.[36]

Ubuntu packages are based on packages from Debian's unstable branch, which are synchronised every six months. Both distributions use Debian's deb package format and package management tools (e.g. APT and Ubuntu Software). Debian and Ubuntu packages are not necessarily binary compatible with each other, however, so packages may need to be rebuilt from source to be used in Ubuntu.[37] Many Ubuntu developers are also maintainers of key packages within Debian. Ubuntu cooperates with Debian by pushing changes back to Debian,[38] although there has been criticism that this does not happen often enough. Ian Murdock, the founder of Debian, had expressed concern about Ubuntu packages potentially diverging too far from Debian to remain compatible.[39] Before release, packages are imported from Debian unstable continuously and merged with Ubuntu-specific modifications. One month before release, imports are frozen, and packagers then work to ensure that the frozen features interoperate well together.

Ubuntu is currently funded by Canonical Ltd. On 8 July 2005, Mark Shuttleworth and Canonical announced the creation of the Ubuntu Foundation and provided initial funding of US$10 million. The purpose of the foundation is to ensure the support and development for all future versions of Ubuntu. Mark Shuttleworth describes the foundation goal as to ensure the continuity of the Ubuntu project.[40]

On 12 March 2009, Ubuntu announced developer support for third-party cloud management platforms, such as those used at Amazon EC2.[41]

GNOME 3 has been the default GUI for Ubuntu Desktop,[42][43] while Unity is still the default in old versions,[44][45] up to 18.04 LTS.[46] Shuttleworth wrote on 8 April 2017, "We will invest in Ubuntu GNOME with the intent of delivering a fantastic all-GNOME desktop. We're helping the Ubuntu GNOME team, not creating something different or competitive with that effort. While I am passionate about the design ideas in Unity, and hope GNOME may be more open to them now, I think we should respect the GNOME design leadership by delivering GNOME the way GNOME wants it delivered. Our role in that, as usual, will be to make sure that upgrades, integration, security, performance and the full experience are fantastic."[47] Shuttleworth also mentioned that Canonical will cease development for Ubuntu Phone, Tablet, and convergence.[48]

32-bit i386 processors have been supported up to Ubuntu 18.04, but users "will not be allowed to upgrade to Ubuntu 18.10 as dropping support for that architecture is being evaluated".[49] It was decided to support "legacy software", i.e. select 32-bit i386 packages for Ubuntu 19.10 and 20.04 LTS.[50]

A default installation of Ubuntu contains a wide range of software that includes LibreOffice, Firefox, Thunderbird, Transmission, and several lightweight games such as Sudoku and chess.[51][52] Many additional software packages are accessible from the built in Ubuntu Software (previously Ubuntu Software Center) as well as any other APT-based package management tools. Many additional software packages that are no longer installed by default, such as Evolution, GIMP, Pidgin, and Synaptic, are still accessible in the repositories and installable by the main tool or by any other APT-based package management tool. Cross-distribution snap packages and flatpaks are also available,[53] that both allow installing software, such as some of Microsoft's software, in most of the major Linux operating systems (such as any currently supported Ubuntu version and in Fedora). The default file manager is GNOME Files, formerly called Nautilus.

All of the application software installed by default is free software. In addition, Ubuntu redistributes some hardware drivers that are available only in binary format, but such packages are clearly marked in the restricted component.[54]

Ubuntu aims to be secure by default.[55][56] User programs run with low privileges and cannot corrupt the operating system or other users' files. For increased security, the sudo tool is used to assign temporary privileges for performing administrative tasks, which allows the root account to remain locked and helps prevent inexperienced users from inadvertently making catastrophic system changes or opening security holes.[57] Polkit is also being widely implemented into the desktop.

Most network ports are closed by default to prevent hacking.[58] A built-in firewall allows end-users who install network servers to control access. A GUI (GUI for Uncomplicated Firewall) is available to configure it.[59] Ubuntu compiles its packages using GCC features such as PIE and buffer overflow protection to harden its software.[60] These extra features greatly increase security at the performance expense of 1% in 32-bit and 0.01% in 64-bit.[61]

Ubuntu also supports full disk encryption[62] as well as encryption of the home and Private directories.[63]

The system requirements vary among Ubuntu products. For the Ubuntu desktop release 20.04 LTS, a PC with at least 2 GHz dual-core processor, 4 GB of RAM and 25 GB of free disk space is recommended.[64][65] For less powerful computers, there are other Ubuntu distributions such as Lubuntu and Xubuntu. Ubuntu supports the ARM architecture.[5][66][67][68][69] It is also available on Power ISA,[5][70][71][72] while older PowerPC architecture was at one point unofficially supported,[73] and now newer Power ISA CPUs (POWER8) are supported. x86 64 a.k.a. AMD64 architecture is also officially supported.

Live images are the typical way for users to assess and subsequently install Ubuntu. These can be downloaded as a disk image (.iso) and subsequently burnt to a DVD and booted. Other methods include running the live version via UNetbootin, or Startup Disk Creator (a pre-installed tool on Ubuntu, available on machines already running the OS) directly from a USB drive (making, respectively, a live DVD or live USB medium). Running Ubuntu in this way is slower than running it from a hard drive, but does not alter the computer unless specifically instructed by the user. If the user chooses to boot the live image rather than execute an installer at boot time, there is still the option to then use an installer called Ubiquity to install Ubuntu once booted into the live environment.[74] Disk images of all current and past versions are available for download at the Ubuntu web site.[75] Various third-party programs such as Reconstructor are available to create customized copies of the Ubuntu Live DVDs (or CDs). "Minimal CDs" are available (for server use) that fit on a CD.

Additionally, USB flash drive installations can be used to boot Ubuntu and Kubuntu in a way that allows permanent saving of user settings and portability of the USB-installed system between physical machines (however, the computers' BIOS must support booting from USB).[76] In newer versions of Ubuntu, the Ubuntu Live USB creator can be used to install Ubuntu on a USB drive (with or without a live CD or DVD). Creating a bootable USB drive with persistence is as simple as dragging a slider to determine how much space to reserve for persistence; for this, Ubuntu employs casper.[77][78]

The desktop edition can also be installed using the Netboot image (a.k.a. netboot tarball) which uses the debian-installer and allows certain specialist installations of Ubuntu: setting up automated deployments, upgrading from older installations without network access, LVM or RAID partitioning, installs on systems with less than about 256 MB of RAM (although low-memory systems may not be able to run a full desktop environment reasonably).[79]

Ubuntu divides most software into four domains to reflect differences in licensing and the degree of support available.[80] Some unsupported applications receive updates from community members, but not from Canonical Ltd.

Free software includes software that has met the Ubuntu licensing requirements,[80] which roughly correspond to the Debian Free Software Guidelines. Exceptions, however, include firmware, in the Main category, because although some firmware is not allowed to be modified, its distribution is still permitted.[81]

Non-free software is usually unsupported (Multiverse), but some exceptions (Restricted) are made for important non-free software. Supported non-free software includes device drivers that can be used to run Ubuntu on some current hardware, such as binary-only graphics card drivers. The level of support in the Restricted category is more limited than that of Main, because the developers may not have access to the source code. It is intended that Main and Restricted should contain all software needed for a complete desktop environment.[80] Alternative programs for the same tasks and programs for specialized applications are placed in the Universe and Multiverse categories.

In addition to the above, in which the software does not receive new features after an initial release, Ubuntu Backports is an officially recognized repository for backporting newer software from later versions of Ubuntu.[82] The repository is not comprehensive; it consists primarily of user-requested packages, which are approved if they meet quality guidelines. Backports receives no support at all from Canonical, and is entirely community-maintained.

The -updates repository provides stable release updates (SRU) of Ubuntu and are generally installed through update-manager. Each release is given its own -updates repository (e.g. intrepid-updates). The repository is supported by Canonical Ltd. for packages in main and restricted, and by the community for packages in universe and multiverse. All updates to the repository must meet certain requirements and go through the -proposed repository before being made available to the public.[83] Updates are scheduled to be available until the end of life for the release.

In addition to the -updates repository, the unstable -proposed repository contains uploads that must be confirmed before being copied into -updates. All updates must go through this process to ensure that the patch does truly fix the bug and there is no risk of regression.[84] Updates in -proposed are confirmed by either Canonical or members of the community.

Canonical's partner repository lets vendors of proprietary software deliver their products to Ubuntu users at no cost through the same familiar tools for installing and upgrading software.[85] The software in the partner repository is officially supported with security and other important updates by its respective vendors. Canonical supports the packaging of the software for Ubuntu[86][87][88] and provides guidance to vendors.[85] The partner repository is disabled by default and can be enabled by the user.[89] Some popular products distributed via the partner repository as of 28 April 2013 are Adobe Flash Player, Adobe Reader and Skype. The free software Wine compatibility layer can be installed to allow users to run Windows software.

Each Ubuntu release has a version number that consists of the year and month number of the release.[104] For example, the first release was Ubuntu 4.10 as it was released on 20 October 2004.

Ubuntu releases are also given alliterative code names, using an adjective and an animal (e.g. "Xenial Xerus"). With the exception of the first two releases, code names are in alphabetical order, allowing a quick determination of which release is newer, at least until restarting the cycle with the release of Artful Aardvark in October 2017.[105] Commonly, Ubuntu releases are referred to using only the adjective portion of the code name; for example, the 18.04 LTS release is commonly known as "Bionic". Releases are timed to be approximately one month after GNOME releases.

Upgrades from one LTS release to the next LTS release (e.g. Ubuntu 16.04 LTS to Ubuntu 18.04 LTS and then to Ubuntu 20.04 LTS) are supported,[106] while upgrades from non-LTS have only supported upgrade to the next release, regardless of its LTS status (e.g. Ubuntu 15.10 to Ubuntu 16.04 LTS). However, it is possible to skip an LTS upgrade, going straight from 16.04 LTS to 18.04.5 LTS, by waiting for a point release that supports such updating.

LTS releases have optional extended security maintenance (ESM) support available, including 14.04 "Trusty"[107] that is otherwise out of public support, adding support for that version up to 2022.[94]

Ubuntu 10.10 (Maverick Meerkat), was released on 10 October 2010 (10–10–10). This departed from the traditional schedule of releasing at the end of October in order to get "the perfect 10",[108] and makes a playful reference to The Hitchhiker's Guide to the Galaxy books, since, in binary, 101010 equals decimal 42, the "Answer to the Ultimate Question of Life, the Universe and Everything" within the series.[109]

Ubuntu (16.04.5 and later) requires a 2 GB or larger installation medium.[110][111] However, there is an option to install it with a Minimal CD.[112]

Ubuntu family tree

Ubuntu Desktop (formally named as Ubuntu Desktop Edition, and simply called Ubuntu) is the variant officially recommended for most users. It is designed for desktop and laptop PCs and officially supported by Canonical. From Ubuntu 17.10, GNOME Shell is the default desktop environment. From Ubuntu 11.04 to Ubuntu 17.04, the Unity desktop interface was the default. A number of other variants are distinguished simply by each featuring a different desktop environment.[75] LXQt and Xfce[113] are often recommended for use with older PCs that may have less memory and processing power available.

Official distributions

Most Ubuntu editions and flavours simply install a different set of default packages compared to the standard Ubuntu Desktop. Since they share the same package repositories, all of the same software is available for each of them.[114][115] Ubuntu Core is the sole exception as it only has access to packages in the Snap Store.[116]

Distribution		Description
	Kubuntu	An Ubuntu flavour using the KDE interface instead of the GNOME and Unity interfaces used by Ubuntu Desktop.[117]
	Lubuntu	Lubuntu is an Ubuntu flavour that is "lighter, less resource hungry and more energy-efficient", using the LXQt desktop environment (used LXDE before 18.10).[118][119][120]
	Ubuntu Core	An Ubuntu edition focussed on IoT and embedded systems. Unlike other variants, it does not use the traditional apt package manager but relies entirely on Snap packages.[121]
	Ubuntu Budgie	An Ubuntu flavour using Budgie.
	Ubuntu Kylin	An Ubuntu flavour aimed at the Chinese market.
	Ubuntu MATE	An Ubuntu flavour using MATE, a desktop environment forked from the now-defunct GNOME 2 code base, with an emphasis on the desktop metaphor.[122]
	Ubuntu Server	Ubuntu has a server edition[123][124] that uses the same APT repositories as the Ubuntu Desktop Edition. The differences between them are the absence of an X Window environment in a default installation of the server edition (although one can easily be installed, including Unity, GNOME, KDE or Xfce), and some alterations to the installation process.[125] The server edition uses a screen-mode, character-based interface for the installation, instead of a graphical installation process. This enables installation on machines with a serial or "dumb terminal" interface without graphics support. The server edition (like the desktop version) supports hardware virtualization and can be run in a virtual machine, either inside a host operating system or in a hypervisor, such as VMware ESXi, Oracle, Citrix XenServer, Microsoft Hyper-V, QEMU, a Kernel-based Virtual Machine, or any other IBM PC compatible emulator or virtualizer. AppArmor security module for the Linux kernel is used by default on key software packages, and the firewall is extended to common services used by the operating system. Runs on all major (64-bit) architectures – x86-64, ARM v7, ARM64, POWER8[126] and later, IBM System z mainframes via LinuxONE,[127] and has initial support for RISC-V. 32-bit x86 are still supported in older Ubuntu Server versions. SPARC is no longer commercially supported. Supports ZFS, a file system with snapshot capabilities, since Ubuntu 16.04 LTS.[128][129][130] Has LXD, a hypervisor to manage LXC Linux containers. Includes the first production release of DPDK for line-speed kernel networking. Uses the latest long-term release Linux kernel and systemd service manager. Is certified as a guest on AWS, Microsoft Azure, Joyent, IBM and HP Cloud.[127] Netplan support[123] (available since Ubuntu 16.04 LTS) snap package manager LVM encryption support It has versions of key server software pre-installed, including: Tomcat, PostgreSQL (v12.2), Docker, Puppet, Python (v3.8), PHP (v7.4), NGINX (v1.17), and MySQL (v8.0).
	Ubuntu Studio	Based on Ubuntu, providing open-source applications for multimedia creation aimed at the audio, video and graphic editors.[131]
	Xubuntu	An Ubuntu flavour using Xfce. Xubuntu is intended for use on less-powerful computers or those who seek a highly efficient desktop environment on faster systems, and uses mostly GTK+ applications.[132]

Ubuntu had some official distributions that have been discontinued, such as Edubuntu; including some previously supported by Canonical, like Ubuntu Touch, that is now maintained by volunteers (UBports Community).

Cloud computing

Cloud Ubuntu Orange Box

Ubuntu offers Ubuntu Cloud Images which are pre-installed disk images that have been customized by Ubuntu engineering to run on cloud-platforms such as Amazon EC2, OpenStack, Microsoft Azure and LXC.[133] Ubuntu is also prevalent on VPS platforms such as DigitalOcean.[134] Ubuntu has support for OpenStack, with Eucalyptus to OpenStack migration tools added by Canonical.[135][136] Ubuntu 11.10 added focus on OpenStack as the Ubuntu's preferred IaaS offering though Eucalyptus is also supported. Another major focus is Canonical Juju for provisioning, deploying, hosting, managing, and orchestrating enterprise data center infrastructure services, by, with, and for the Ubuntu Server.[137][138]

Eucalyptus interface

In an effort to reach out to users who are less technical, and to foster a sense of community around the distribution, Local Communities,[186] better known as "LoCos", have been established throughout the world. Originally, each country had one LoCo Team. However, in some areas, most notably the United States and Canada, each state or province may establish a team.[187] A LoCo Council approves teams based upon their efforts to aid in either the development or the promotion of Ubuntu.[188]

Ubuntu works closely with OEMs to jointly make Ubuntu available on a wide range of devices.[189] A number of vendors offer computers with Ubuntu pre-installed, including Dell,[190] Hasee,[191] Sharp Corporation, and Cirrus7.[192][193] Specifically, Dell offers the XPS 13 laptop, Developer Edition with Ubuntu pre-installed.[194] Together, Dell, Lenovo, HP, and Acer offer over 200 desktop and over 400 laptop PCs preloaded with Ubuntu.[195] System76 PCs are also sold with Ubuntu.[196] Dell and System76 customers are able to choose between 30-day, three-month, and yearly Ubuntu support plans through Canonical.[197] Dell computers (running Ubuntu 10.04) include extra support for ATI/AMD Video Graphics, Dell Wireless, Fingerprint Readers, HDMI, Bluetooth, DVD playback (using LinDVD), and MP3/WMA/WMV.[198] Asus is also selling some Eee PCs with Ubuntu pre-installed and announced "many more" models running Ubuntu for 2011.[199][200][201] Vodafone has made available a notebook for the South-African market called "Webbook".[202][203][204]

Dell sells computers (initially Inspiron 14R and 15R laptops) pre-loaded with Ubuntu in India and China, with 850 and 350 retail outlets respectively.[205][206] Starting in 2013, Alienware began offering its X51 model gaming desktop pre-installed with Ubuntu at a lower price than if it were pre-installed with Windows.[207]

While Linux already works on IBM's mainframe system (Linux on IBM Z), IBM in collaboration with Canonical (and SUSE; "Linux Foundation will form a new Open Mainframe Project") announced Ubuntu support for their z/Architecture for the first time (IBM claimed their system, IBM zEnterprise System, version z13, the most powerful computer in the world in 2015;[208] it was then the largest computer by transistor count; again claimed fastest in 2017 with IBM z14[209]), at the time of their "biggest code drop" ("LinuxOne") in Linux history.[210]

In early 2015, Intel launched the Intel Compute Stick small form factor computer available preloaded with Ubuntu or Windows operating systems.[211]

In March 2016, Microsoft announced that it would support the Ubuntu userland on top of the Windows 10 kernel by implementing the Linux system calls as a subsystem (and in 2019 Microsoft announced the new WSL 2 subsystem that includes a Linux kernel, that Canonical announced will have "full support for Ubuntu"[17]). It focuses on command-line tools like Bash and is therefore aimed at programmers.[212][213][214] As of the Fall Creators Update (1709), this feature is fully available to the public.[215] As of 2019, other Linux variants are also supported.

• Comparison of operating systems

• Official website
• Ubuntu at DistroWatch