The Advanced packaging tool, or APT, is a user interface that works with core libraries to handle the sometimes difficult process of installing software on Linux. APT simplifies the process of managing software on Unix-like computer systems by automating the retrieval, configuration and installation of software packages, either from binary files or by compiling source code. A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer. ... C is a general-purpose, block structured, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ... An operating system (OS) is a software that manages computer resources and provides programmers with an interface used to access those resources. ... A cross-platform (or platform independent) programming language, software application or hardware device works on more than one system platform (e. ... In computing, a platform describes some sort of framework, either in hardware or software, which allows software to run. ... Debian is a free operating system. ... Illustration of a package management system being used to download new software. ... A software license is a legal agreement which may take the form of a proprietary or gratuitous license as well as a memorandum of contract between a producer and a user of computer software. ... GPL redirects here. ... In their most general meanings, the terms front end and back end refer to the initial and the end stages of a process flow. ... In computer science, a library is a collection of subprograms used to develop software. ... This article is about operating systems that use the Linux kernel. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... A software package is a bundle of one or several files that either are necessary for the execution of a computer program, or add features for a program already installed on the computer or network of computers. ... A compiler is a computer program that translates a computer program written in one computer language (called the source language) into an equivalent program written in another computer language (called the output or the target language). ...

APT was originally designed as a front-end for dpkg to work with Debian's .deb packages, but it has since been modified to work with the RPM Package Manager system via apt-rpm. The Fink project has ported APT to Mac OS X for some of its own package management tasks, and APT is also available in OpenSolaris (included in Nexenta OS distribution). dpkg (short for Debian PacKaGe) is the base of the Debian package management system. ... deb is the extension of the Debian software package format and the most often used name for such binary packages. ... RPM Package Manager (originally Red Hat Package Manager, abbreviated RPM) is a package management system. ... apt-rpm is a version of the Advanced Packaging Tool modified to work with the RPM Package Manager. ... In computing, the Fink project is an effort to port Unix programs to Mac OS X. Fink uses dpkg and APT (Debians package management system), as well as its own frontend program, fink (which is implemented as a set of Perl modules). ... Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... OpenSolaris is an open source project created by Sun Microsystems to build a developer community around Solaris Operating System technology. ... Nexenta OS is a port of Debian to the OpenSolaris kernel. ...

Distributed under the GNU General Public License, APT is free software. GPL redirects here. ... Free software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with minimal restrictions only to ensure that further recipients can also do these things. ...

Usage

There is no single "apt" program as such; APT is a C++ library of functions (known as libapt) which are used by front-end programs for dealing with packages, such as apt-get and apt-cache. They are commonly used in examples due to their simplicity and ubiquity; apt-get and apt-cache are of "important" priority in all current Debian releases, and are therefore installed in a default Debian installation. C++ (pronounced ) is a general-purpose programming language. ...

Several other front-ends to APT exist, which provide more advanced installation functions and more intuitive interfaces. These include: In their most general meanings, the terms front end and back end refer to the initial and the end stages of a process flow. ...

• Synaptic Package Manager, a GTK+ / KDE graphical user interface
• aptitude, a versatile alternative to dselect
• KPackage, part of KDE
• Adept Package Manager, a graphical user interface for KDE (deb, rpm, bsd)
• PackageKit, a freedesktop.org frontend.
• apt-cdrom, to add a new CDROM to APTs list of available sources.lists (list of available repositories). It is necessary to use apt-cdrom to add CDs to the APT system, it cannot be done by hand.
• apt-zip, use apt with removable media, specially USB keydrives.
• apt:foo downloading and installing software by clicking on a web-link (experimental) ^[1]

APT front-ends can: A screenshot of Synaptic. ... GTK+, or the GIMP Toolkit, is one of the two most popular widget toolkits for the X Window System for creating graphical user interfaces. ... GUI redirects here. ... aptitude is a front-end to APT. It displays a list of software packages and allows the user to interactively pick packages to install or remove. ... Advanced Packaging Tool, or APT, is a package management system used by Debian and its derivatives. ... The subject of this article may not satisfy the notability guideline or one of the following guidelines for inclusion on Wikipedia: Biographies, Books, Companies, Fiction, Music, Neologisms, Numbers, Web content, or several proposals for new guidelines. ... For the NYSE stock ticker symbol KDE, see 4Kids Entertainment. ... A screenshot of Adept Adept [1] is a GUI to the Advanced Packaging Tool for KDE. Adept is developed by Peter Rockai and is sponsored by Canonical Ltd through the Kubuntu project. ... For the NYSE stock ticker symbol KDE, see 4Kids Entertainment. ... freedesktop. ... Removable media are transportable drives or disks that can be moved easily from one computer to another. ...

• search for new packages;
• upgrade packages;
• install or remove packages;
• upgrade the whole system to a new release.

APT front-ends can list the dependencies of packages being installed or upgraded, ask the administrator if packages recommended or suggested by newly installed packages should be installed too, automatically install dependencies and perform other operations on the system such as removing obsolete files and packages.

APT is often hailed as one of Debian's best features.^[2]

A major feature in APT is the way it calls dpkg - it does topological sorting of the list of packages to be installed or removed and calls dpkg in the best possible sequence. In some cases, it utilizes the --force options in dpkg, whenever it is able to calculate how to avoid the reasons why dpkg requires actions to be forced. In graph theory, a topological sort of a directed acyclic graph (DAG) is a linear ordering of its nodes which is compatible with the partial order R induced on the nodes where x comes before y (xRy) if theres a directed path from x to y in the DAG...

Other than install, the other most used apt-get commands are apt-get update, apt-get upgrade and apt-get dist-upgrade.

Install

Install is followed by one or more packages desired for installation. Each package is a package name, not a fully qualified filename (for instance, in a Debian GNU/Linux system, libc6 would be the argument provided, not libc6_1.9.6-2.deb). All packages required by the package(s) specified for installation will also be retrieved and installed. The /etc/apt/sources.list file is used to locate the desired packages. If a hyphen is appended to the package name (with no intervening space), the identified package will be removed if it is installed. Similarly a plus sign can be used to designate a package to install. These latter features may be used to override decisions made by apt-get's conflict resolution system.

A specific version of a package can be selected for installation by following the package name with an equals and the version of the package to select. This will cause that version to be located and selected for install. Alternatively a specific distribution can be selected by following the package name with a slash and the version of the distribution or the Archive name (stable, testing, unstable).

Both of the version selection mechanisms can downgrade packages and must be used with care.

Finally, the apt_preferences mechanism allows creating an alternative installation policy for individual packages.

If no package matches the given expression and the expression contains one of '.', '?' or '*' then it is assumed to be a POSIX regular expression, and it is applied to all package names in the database. Any matches are then installed (or removed). Note that matching is done by substring so 'lo.*' matches 'how-lo' and 'lowest'. If this is undesired, anchor the regular expression with a '^' or '$' character, or create a more specific regular expression.

Update, upgrade and dist-upgrade

• Update is used to resynchronize the package index files from their sources. The indexes of available packages are fetched from the location(s) specified in /etc/apt/sources.list. For example, when using a Debian archive, this command retrieves and scans the Packages.gz files, so that information about new and updated packages is available. An update should always be performed before an upgrade or dist-upgrade. Be aware that the overall progress meter will be incorrect as the size of the package files cannot be known in advance.

• Upgrade is used to install the newest versions of all packages currently installed on the system from the sources enumerated in /etc/apt/sources.list. Packages currently installed with new versions available are retrieved and upgraded; under no circumstances are currently installed packages removed, or packages not already installed retrieved and installed. New versions of currently installed packages that cannot be upgraded without changing the install status of another package will be left at their current version. An update must be performed first so that apt-get knows that new versions of packages are available.

• dist-upgrade, in addition to performing the function of upgrade, also intelligently handles changing dependencies with new versions of packages; apt-get has a "smart" conflict resolution system, and it will attempt to upgrade the most important packages at the expense of less important ones if necessary. The /etc/apt/sources.list file contains a list of locations from which to retrieve desired package files.

Configuration and Files

/etc/apt has the apt configuration folders and files.

apt-config is the APT Configuration Query program. ^[3] apt-config dump shows the configuration. ^[4]

Files

• /etc/apt/sources.list : Locations to fetch packages from.
• /etc/apt/apt.conf : APT configuration file.
• /etc/apt/apt.conf.d/ : APT configuration file fragments .
• /etc/apt/preferences : version preferences file. This is where you would specify "pinning", i.e. a preference to get certain packages from a separate source or from a different version of a distribution.
• /var/cache/apt/archives/ : storage area for retrieved package files. * /var/cache/apt/archives/partial/  : storage area for package files in transit. * /var/lib/apt/lists/ : storage area for state information for each package resource specified in sources.list
• /var/lib/apt/lists/partial/  : storage area for state information in transit.

Sources

APT relies on the concept of repositories in order to find software and resolve dependencies. For apt, a repository is a directory containing packages along with an index file. The Debian project keeps a central repository of over 19,000 software packages ready for download and installation. A software repository is a storage location from which software packages may be be retrieved and installed on a computer. ...

For extra packages, any number of additional repositories can be added to APT's sources.list configuration file (/etc/apt/sources.list) and then be queried by APT. Graphical front-ends often allow modify source.list more simply (apt-setup). Once a package repository has been specified (like during the system installation), packages in that repository can be installed without specifying a source.

In addition to network repositories, compact discs and other storage media (USB keydrive, hard disks...) can be used as well, using apt-cdrom ^[5] or adding file:/ ^[6] to the source list file. Apt-cdrom can specify a different folder than a cd-rom, using the -d option (i.e. a hard disk or a USB keydrive). The Debian CDs available for download contain Debian repositories. This allows non-networked machines to be upgraded. Also one can use apt-zip. CD redirects here. ...

Problems may appear when several sources offer the same package(s). Systems that have such possibly conflicting sources can use APT pinning to control which sources should be preferred.

APT pinning

APT pinning is a feature which allows administrators to force APT to choose particular versions of packages which may be available in different versions from different repositories. This allows administrators to ensure that packages are not upgraded to versions which may conflict with other packages on the system, or that have not been sufficiently tested for unwelcome changes.

In order to do this, the pins in APT's preferences file (/etc/apt/preferences) must be modified,^[7] although graphical front-ends often allow this more simply.

History

The original effort that led to the apt-get program was the dselect replacement project known by its codename deity.^[8] This project was commissioned by Brian White, the Debian Release Manager at the time. The very first functional version of apt-get was called dpkg-get and was only intended to be a test program for the core library functions that would underpin the new UI.^[9]

Much of the original development of APT was done on IRC so records have been lost. The 'Deity Creation Team' mailing list archives include only the major highlights.

The Deity name was abandoned as the official name for the project due to concerns over the religious nature of the name. The APT name was eventually decided after considerable internal and public discussion. Ultimately the name was proposed on IRC, accepted and then finalized on the mailing lists.^[10] As originally used APT is not an acronym, but a proper name. The name gained mindshare during IRC discussions^{[citation needed]} due to the variety of possible acronym expansions and it was ultimately decided that the official use of APT would be as a proper name and no official expansion would ever be presented by the team.

APT was introduced in 1998 and original test builds were circulated on IRC. The first Debian version that included it was Debian 2.1, released on 9 March 1999.^[11] is the 68th day of the year (69th in leap years) in the Gregorian calendar. ... Events of 2008: (EMILY) Me Lesley and MIley are going to China! This article is about the year. ...

In the end the original goal of the Deity project of replacing the dselect UI was a failure. Work on the user interface (UI) portion of the project was abandoned (the UI directories were removed from the CVS system) after the first public release of apt-get. The response to APT as a dselect method and a command line utility was so great and positive that all development efforts focused on maintaining and improving the tool. It wasn't until much later that several independent people built UIs on top of the capable libapt-pkg. The Concurrent Versions System (CVS), also known as the Concurrent Versioning System, is an open-source version control system invented and developed by Dick Grune in the 1980s. ...

The final push of the first APT era was to build a complete dpkg replacement (libapt-inst). This project was also a failure, however the partial code found a use as part of the secretive 'Project Betsy' programme, which resulted in the highly efficient apt-ftparchive and libapt python bindings. After this the original author faded away and maintainership of APT languished.

Eventually a new team picked up the project, began to build new features and released version 0.6 of APT which introduced the Secure APT feature, using strong cryptographic signing to authenticate the package repositories.^[12] The GNU Privacy Guard (GnuPG or GPG) is a free software replacement for the PGP suite of cryptographic software, released under the GNU General Public License. ... A digital signature or digital signature scheme is a type of asymmetric cryptography used to simulate the security properties of a signature in digital, rather than written, form. ...

See also

• Alien
• Linux Standard Base
• Nexenta
• PackageKit
• PISI
• Pkgsrc
• Portage (software)
• Ports collection
• Wajig
• apt:foo

Image File history File links Free_Software_Portal_Logo. ... Alien is a computer program that converts between different Linux package formats. ... The Linux Standard Base, or LSB, is a joint project by several GNU/Linux distributions under the organizational structure of The Free Standards Group to standardize the internal structure of Linux-based operating systems. ... In computing, Nexenta OS is an Debian-based GNU/Solaris operating system. ... Pardus is a GNU/Linux distribution which is developed in Turkey, as a product of the UludaÄŸ Project. ... pkgsrc (package source) is a package management system for Unix-like operating systems. ... Portage is an advanced package management system. ... Ports collections (or ports trees, or just ports) are the sets of makefiles and patches provided by the BSD-based operating systems, FreeBSD, NetBSD and OpenBSD, as a simple method of installing software or creating binary packages. ... Wajig is a simplified front end to the underlying package management toolss including dpkg and APT for Debian GNU/Linux. ...

References

Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 262nd day of the year (263rd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 248th day of the year (249th in leap years) in the Gregorian calendar. ...

External links

• apt-get Manual page
• APT HOWTO
• apt-cache
• apt.conf
• apt_preferences
• apt offline
• apt-zip:
  • Offline functionality.
• pypt-offline
• Adding source lists using apt-setup
• apt-cdrom