Ubuntu

**Ubuntu** is a free and open-source Linux distribution based on Debian. Ubuntu is officially released in three editions: *Desktop*, *Server*, and *Core* (for internet of things devices and robots). All the editions can run on the computer alone, or e.g. in Windows. Ubuntu is a popular operating system for cloud computing, with support for OpenStack.

Ubuntu is released every six months, with long-term support (LTS) releases every two years. The latest release is 19.04 ("Disco Dingo"), and the most recent long-term support release is 18.04 LTS ("Bionic Beaver"), which is supported until 2023 under public support and until 2028 as a paid option.

Ubuntu is developed by Canonical and the community under a meritocratic governance model. Canonical provides security updates and support for each Ubuntu release, starting from the release date and until the release reaches its designated end-of-life (EOL) date. Canonical generates revenue through the sale of premium services related to Ubuntu.

Ubuntu is named after the African philosophy of *ubuntu*, which Canonical translates as "humanity to others" or "I am what I am because of who we all are".

## Features

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. 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 still installable by the main tool or by any other APT-based package management tool. Cross-distribution snap packages and flatpaks are also available, 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.

Ubuntu operates under the GNU General Public License (GPL) and all of the application software installed by default is free software. In addition, Ubuntu installs some hardware drivers that are available only in binary format, but such packages are clearly marked in the restricted component.

## Security

Ubuntu aims to be secure by default. 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. Polkit is also being widely implemented into the desktop.

Most network ports are closed by default to prevent hacking. 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. Ubuntu compiles its packages using GCC features such as PIE and buffer overflow protection to harden its software. These extra features greatly increase security at the performance expense of 1% in 32-bit and 0.01% in 64-bit.

Ubuntu also supports full disk encryption as well as encryption of the home and Private directories.

## Installation

The system requirements vary among Ubuntu products. For the Ubuntu desktop release 16.04 LTS, a PC with at least 2 GHz dual-core processor, 2 GB of RAM and 25 GB of free disk space is recommended. For less powerful computers, there are other Ubuntu distributions such as Lubuntu and Xubuntu. Ubuntu supports the ARM architecture. It is also available on Power ISA, while older PowerPC architecture was at one point unofficially supported, and now newer Power ISA CPUs (POWER8) are 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, or run via UNetbootin 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. Disk images of all current and past versions are available for download at the Ubuntu web site. Various third-party programs such as remastersys and 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). 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.

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).

## Package classification and support

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

 Unsupported

Free software includes software that has met the Ubuntu licensing requirements, 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, their distribution is still permitted.

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. 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. 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. 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 which 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. 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. 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 and provides guidance to vendors. The partner repository is disabled by default and can be enabled by the user. Some popular products distributed via the partner repository as of 28 April 2013[update] are Adobe Flash Player, Adobe Reader, Skype and Wine are also able to be installed to run Windows software if the user desires.

### Package Archives

A Personal Package Archive (PPA) is a software repository for uploading source packages to be built and published as an Advanced Packaging Tool (APT) repository by Launchpad. While the term is used exclusively within Ubuntu, Launchpad's host, Canonical, envisions adoption beyond the Ubuntu community.

### Third-party software

See also: GetDeb
Ubuntu has a certification system for third-party software. Some third-party software that does not limit distribution is included in Ubuntu's multiverse component. The package *ubuntu-restricted-extras* additionally contains software that may be legally restricted, including support for MP3 and DVD playback, Microsoft TrueType core fonts, Sun's Java runtime environment, Adobe's Flash Player plugin, many common audio/video codecs, and unrar, an unarchiver for files compressed in the RAR file format.

Additionally, third-party application suites are available for purchase through Ubuntu Software, including many games such as Braid and Oil Rush, software for DVD playback and media codecs.

## Windows subsystem

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"). It focuses on command-line tools like Bash and is therefore aimed at programmers. As of the Fall Creators Update, this feature is fully available to the public. As of 2019, other Linux variants are also supported.