Provided by: apt_1.6~rc1_amd64 bug

NAME

       sources.list - List of configured APT data sources

DESCRIPTION

       The source list /etc/apt/sources.list and the files contained in
       /etc/apt/sources.list.d/ are designed to support any number of active
       sources and a variety of source media. The files list one source per
       line (one-line style) or contain multiline stanzas defining one or more
       sources per stanza (deb822 style), with the most preferred source
       listed first (in case a single version is available from more than one
       source). The information available from the configured sources is
       acquired by apt-get update (or by an equivalent command from another
       APT front-end).

SOURCES.LIST.D

       The /etc/apt/sources.list.d directory provides a way to add
       sources.list entries in separate files. Two different file formats are
       allowed as described in the next two sections. Filenames need to have
       either the extension .list or .sources depending on the contained
       format. The filenames may only contain letters (a-z and A-Z), digits
       (0-9), underscore (_), hyphen (-) and period (.) characters. Otherwise
       APT will print a notice that it has ignored a file, unless that file
       matches a pattern in the Dir::Ignore-Files-Silently configuration list
       - in which case it will be silently ignored.

ONE-LINE-STYLE FORMAT

       Files in this format have the extension .list. Each line specifying a
       source starts with a type (e.g.  deb-src) followed by options and
       arguments for this type. Individual entries cannot be continued onto a
       following line. Empty lines are ignored, and a # character anywhere on
       a line marks the remainder of that line as a comment. Consequently an
       entry can be disabled by commenting out the entire line. If options
       should be provided they are separated by spaces and all of them
       together are enclosed by square brackets ([]) included in the line
       after the type separated from it with a space. If an option allows
       multiple values these are separated from each other with a comma (,).
       An option name is separated from its value(s) by an equals sign (=).
       Multivalue options also have -= and += as separators, which instead of
       replacing the default with the given value(s) modify the default
       value(s) to remove or include the given values.

       This is the traditional format and supported by all apt versions. Note
       that not all options as described below are supported by all apt
       versions. Note also that some older applications parsing this format on
       their own might not expect to encounter options as they were uncommon
       before the introduction of multi-architecture support.

DEB822-STYLE FORMAT

       Files in this format have the extension .sources. The format is similar
       in syntax to other files used by Debian and its derivatives, such as
       the metadata files that apt will download from the configured sources
       or the debian/control file in a Debian source package. Individual
       entries are separated by an empty line; additional empty lines are
       ignored, and a # character at the start of the line marks the entire
       line as a comment. An entry can hence be disabled by commenting out
       each line belonging to the stanza, but it is usually easier to add the
       field "Enabled: no" to the stanza to disable the entry. Removing the
       field or setting it to yes reenables it. Options have the same syntax
       as every other field: A fieldname separated by a colon (:) and
       optionally spaces from its value(s). Note especially that multiple
       values are separated by whitespaces (like spaces, tabs and newlines),
       not by commas as in the one-line format. Multivalue fields like
       Architectures also have Architectures-Add and Architectures-Remove to
       modify the default value rather than replacing it.

       This is a new format supported by apt itself since version 1.1.
       Previous versions ignore such files with a notice message as described
       earlier. It is intended to make this format gradually the default
       format, deprecating the previously described one-line-style format, as
       it is easier to create, extend and modify for humans and machines alike
       especially if a lot of sources and/or options are involved. Developers
       who are working with and/or parsing apt sources are highly encouraged
       to add support for this format and to contact the APT team to
       coordinate and share this work. Users can freely adopt this format
       already, but may encounter problems with software not supporting the
       format yet.

THE DEB AND DEB-SRC TYPES: GENERAL FORMAT

       The deb type references a typical two-level Debian archive,
       distribution/component. The distribution is generally a suite name like
       stable or testing or a codename like stretch or buster while component
       is one of main, contrib or non-free. The deb-src type references a
       Debian distribution's source code in the same form as the deb type. A
       deb-src line is required to fetch source indexes.

       The format for two one-line-style entries using the deb and deb-src
       types is:

           deb [ option1=value1 option2=value2 ] uri suite [component1] [component2] [...]
           deb-src [ option1=value1 option2=value2 ] uri suite [component1] [component2] [...]

       Alternatively the equivalent entry in deb822 style looks like this:

                Types: deb deb-src
                URIs: uri
                Suites: suite
                Components: [component1] [component2] [...]
                option1: value1
                option2: value2

       The URI for the deb type must specify the base of the Debian
       distribution, from which APT will find the information it needs.  suite
       can specify an exact path, in which case the components must be omitted
       and suite must end with a slash (/). This is useful for the case when
       only a particular sub-directory of the archive denoted by the URI is of
       interest. If suite does not specify an exact path, at least one
       component must be present.

       suite may also contain a variable, $(ARCH) which expands to the Debian
       architecture (such as amd64 or armel) used on the system. This permits
       architecture-independent sources.list files to be used. In general this
       is only of interest when specifying an exact path; APT will
       automatically generate a URI with the current architecture otherwise.

       Especially in the one-line-style format since only one distribution can
       be specified per line it may be necessary to have multiple lines for
       the same URI, if a subset of all available distributions or components
       at that location is desired. APT will sort the URI list after it has
       generated a complete set internally, and will collapse multiple
       references to the same Internet host, for instance, into a single
       connection, so that it does not inefficiently establish a connection,
       close it, do something else, and then re-establish a connection to that
       same host. APT also parallelizes connections to different hosts to more
       effectively deal with sites with low bandwidth.

       It is important to list sources in order of preference, with the most
       preferred source listed first. Typically this will result in sorting by
       speed from fastest to slowest (CD-ROM followed by hosts on a local
       network, followed by distant Internet hosts, for example).

       As an example, the sources for your distribution could look like this
       in one-line-style format:

           deb http://us.archive.ubuntu.com/ubuntu xenial main restricted
           deb http://security.ubuntu.com/ubuntu xenial-security main restricted
           deb http://us.archive.ubuntu.com/ubuntu xenial-updates main restricted

       or like this in deb822 style format:

           Types: deb
           URIs: http://us.archive.ubuntu.com/ubuntu
           Suites: xenial xenial-updates
           Components: main restricted

           Types: deb
           URIs: http://security.ubuntu.com/ubuntu
           Suites: xenial-security
           Components: main restricted

THE DEB AND DEB-SRC TYPES: OPTIONS

       Each source entry can have options specified to modify which source is
       accessed and how data is acquired from it. Format, syntax and names of
       the options vary between the one-line-style and deb822-style formats as
       described, but they both have the same options available. For
       simplicity we list the deb822 fieldname and provide the one-line name
       in brackets. Remember that besides setting multivalue options
       explicitly, there is also the option to modify them based on the
       default, but we aren't listing those names explicitly here. Unsupported
       options are silently ignored by all APT versions.

       ·   Architectures (arch) is a multivalue option defining for which
           architectures information should be downloaded. If this option
           isn't set the default is all architectures as defined by the
           APT::Architectures config option.

       ·   Languages (lang) is a multivalue option defining for which
           languages information such as translated package descriptions
           should be downloaded. If this option isn't set the default is all
           languages as defined by the Acquire::Languages config option.

       ·   Targets (target) is a multivalue option defining which download
           targets apt will try to acquire from this source. If not specified,
           the default set is defined by the Acquire::IndexTargets
           configuration scope (targets are specified by their name in the
           Created-By field). Additionally, targets can be enabled or disabled
           by using the Identifier field as an option with a boolean value
           instead of using this multivalue option.

       ·   PDiffs (pdiffs) is a yes/no value which controls if APT should try
           to use PDiffs to update old indexes instead of downloading the new
           indexes entirely. The value of this option is ignored if the
           repository doesn't announce the availability of PDiffs. Defaults to
           the value of the option with the same name for a specific index
           file defined in the Acquire::IndexTargets scope, which itself
           defaults to the value of configuration option Acquire::PDiffs which
           defaults to yes.

       ·   By-Hash (by-hash) can have the value yes, no or force and controls
           if APT should try to acquire indexes via a URI constructed from a
           hashsum of the expected file instead of using the well-known stable
           filename of the index. Using this can avoid hashsum mismatches, but
           requires a supporting mirror. A yes or no value activates/disables
           the use of this feature if this source indicates support for it,
           while force will enable the feature regardless of what the source
           indicates. Defaults to the value of the option of the same name for
           a specific index file defined in the Acquire::IndexTargets scope,
           which itself defaults to the value of configuration option
           Acquire::By-Hash which defaults to yes.

       Furthermore, there are options which if set affect all sources with the
       same URI and Suite, so they have to be set on all such entries and can
       not be varied between different components. APT will try to detect and
       error out on such anomalies.

       ·   Allow-Insecure (allow-insecure), Allow-Weak (allow-weak) and
           Allow-Downgrade-To-Insecure (allow-downgrade-to-insecure) are
           boolean values which all default to no. If set to yes they
           circumvent parts of apt-secure(8) and should therefore not be used
           lightly!

       ·   Trusted (trusted) is a tri-state value which defaults to APT
           deciding if a source is considered trusted or if warnings should be
           raised before e.g. packages are installed from this source. This
           option can be used to override that decision. The value yes tells
           APT always to consider this source as trusted, even if it doesn't
           pass authentication checks. It disables parts of apt-secure(8), and
           should therefore only be used in a local and trusted context (if at
           all) as otherwise security is breached. The value no does the
           opposite, causing the source to be handled as untrusted even if the
           authentication checks passed successfully. The default value can't
           be set explicitly.

       ·   Signed-By (signed-by) is either an absolute path to a keyring file
           (has to be accessible and readable for the _apt user, so ensure
           everyone has read-permissions on the file) or one or more
           fingerprints of keys either in the trusted.gpg keyring or in the
           keyrings in the trusted.gpg.d/ directory (see apt-key fingerprint).
           If the option is set, only the key(s) in this keyring or only the
           keys with these fingerprints are used for the apt-secure(8)
           verification of this repository. Defaults to the value of the
           option with the same name if set in the previously acquired Release
           file. Otherwise all keys in the trusted keyrings are considered
           valid signers for this repository.

       ·   Check-Valid-Until (check-valid-until) is a yes/no value which
           controls if APT should try to detect replay attacks. A repository
           creator can declare a time until which the data provided in the
           repository should be considered valid, and if this time is reached,
           but no new data is provided, the data is considered expired and an
           error is raised. Besides increasing security, as a malicious
           attacker can't send old data forever to prevent a user from
           upgrading to a new version, this also helps users identify mirrors
           which are no longer updated. However, some repositories such as
           historic archives are not updated any more by design, so this check
           can be disabled by setting this option to no. Defaults to the value
           of configuration option Acquire::Check-Valid-Until which itself
           defaults to yes.

       ·   Valid-Until-Min (valid-until-min) and Valid-Until-Max
           (valid-until-max) can be used to raise or lower the time period in
           seconds in which the data from this repository is considered valid.
           -Max can be especially useful if the repository provides no
           Valid-Until field on its Release file to set your own value, while
           -Min can be used to increase the valid time on seldom updated
           (local) mirrors of a more frequently updated but less accessible
           archive (which is in the sources.list as well) instead of disabling
           the check entirely. Default to the value of the configuration
           options Acquire::Min-ValidTime and Acquire::Max-ValidTime which are
           both unset by default.

       ·   Check-Date (check-date) is a yes/no value which controls if APT
           should consider the machine's time correct and hence perform time
           related checks, such as verifying that a Release file is not from
           the future. Disabling it also disables the Check-Valid-Until option
           mentioned above.

       ·   Date-Max-Future (date-max-future) controls how far from the future
           a repository may be. Default to the value of the configuration
           option Acquire::Max-FutureTime which is 10 seconds by default.

       ·   InRelease-Path (inrelease-path) determines the path to the
           InRelease file, relative to the normal position of an InRelease
           file. By default, this option is unset and APT will try to fetch an
           InRelease or, if that fails, a Release file and its associated
           Release.gpg file. By setting this option, the specified path will
           be tried instead of the InRelease file, and the fallback to Release
           files will be disabled.

URI SPECIFICATION

       The currently recognized URI types are:

       http (apt-transport-http(1))
           The http scheme specifies an HTTP server for an archive and is the
           most commonly used method. The URI can directly include login
           information if the archive requires it, but the use of
           apt_auth.conf(5) should be preferred. The method also supports
           SOCKS5 and HTTP(S) proxies either configured via apt-specific
           configuration or specified by the environment variable http_proxy
           in the format (assuming an HTTP proxy requiring authentication)
           http://user:pass@server:port/. The authentication details for
           proxies can also be supplied via apt_auth.conf(5).

           Note that these forms of authentication are insecure as the whole
           communication with the remote server (or proxy) is not encrypted so
           a sufficiently capable attacker can observe and record login as
           well as all other interactions. The attacker can not modify the
           communication through as APTs data security model is independent of
           the chosen transport method. See apt-secure(8) for details.

       https (apt-transport-https(1))
           The https scheme specifies an HTTPS server for an archive and is
           very similar in use and available options to the http scheme. The
           main difference is that the communication between apt and server
           (or proxy) is encrypted. Note that the encryption does not prevent
           an attacker from knowing which server (or proxy) apt is
           communicating with and deeper analyses can potentially still reveal
           which data was downloaded. If this is a concern the Tor-based
           schemes mentioned further below might be a suitable alternative.

       file
           The file scheme allows an arbitrary directory in the file system to
           be considered an archive. This is useful for NFS mounts and local
           mirrors or archives.

       cdrom
           The cdrom scheme allows APT to use a local CD-ROM, DVD or USB drive
           with media swapping. Use the apt-cdrom(8) program to create cdrom
           entries in the source list.

       ftp
           The ftp scheme specifies an FTP server for an archive. Use of FTP
           is on the decline in favour of http and https and many archives
           either never offered or are retiring FTP access. If you still need
           this method many configuration options for it are available in the
           Acquire::ftp scope and detailed in apt.conf(5).

           Please note that an FTP proxy can be specified by using the
           ftp_proxy environment variable. It is possible to specify an HTTP
           proxy (HTTP proxy servers often understand FTP URLs) using this
           environment variable and only this environment variable. Proxies
           using HTTP specified in the configuration file will be ignored.

       copy
           The copy scheme is identical to the file scheme except that
           packages are copied into the cache directory instead of used
           directly at their location. This is useful for people using
           removable media to copy files around with APT.

       rsh, ssh
           The rsh/ssh method invokes RSH/SSH to connect to a remote host and
           access the files as a given user. Prior configuration of rhosts or
           RSA keys is recommended. The standard find and dd commands are used
           to perform the file transfers from the remote host.

       adding more recognizable URI types
           APT can be extended with more methods shipped in other optional
           packages, which should follow the naming scheme
           apt-transport-method. For instance, the APT team also maintains the
           package apt-transport-tor, which provides access methods for HTTP
           and HTTPS URIs routed via the Tor network.

EXAMPLES

       Uses the archive stored locally (or NFS mounted) at /home/apt/debian
       for stable/main, stable/contrib, and stable/non-free.

           deb file:/home/apt/debian stable main contrib non-free

           Types: deb
           URIs: file:/home/apt/debian
           Suites: stable
           Components: main contrib non-free

       As above, except this uses the unstable (development) distribution.

           deb file:/home/apt/debian unstable main contrib non-free

           Types: deb
           URIs: file:/home/apt/debian
           Suites: unstable
           Components: main contrib non-free

       Sources specification for the above.

           deb-src file:/home/apt/debian unstable main contrib non-free

           Types: deb-src
           URIs: file:/home/apt/debian
           Suites: unstable
           Components: main contrib non-free

       The first line gets package information for the architectures in
       APT::Architectures while the second always retrieves amd64 and armel.

           deb http://deb.debian.org/debian stretch main
           deb [ arch=amd64,armel ] http://deb.debian.org/debian stretch main

           Types: deb
           URIs: http://deb.debian.org/debian
           Suites: stretch
           Components: main

           Types: deb
           URIs: http://deb.debian.org/debian
           Suites: stretch
           Components: main
           Architectures: amd64 armel

       Uses HTTP to access the archive at archive.debian.org, and uses only
       the hamm/main area.

           deb http://archive.debian.org/debian-archive hamm main

           Types: deb
           URIs: http://archive.debian.org/debian-archive
           Suites: hamm
           Components: main

       Uses FTP to access the archive at ftp.debian.org, under the debian
       directory, and uses only the stretch/contrib area.

           deb ftp://ftp.debian.org/debian stretch contrib

           Types: deb
           URIs: ftp://ftp.debian.org/debian
           Suites: stretch
           Components: contrib

       Uses FTP to access the archive at ftp.debian.org, under the debian
       directory, and uses only the unstable/contrib area. If this line
       appears as well as the one in the previous example in sources.list a
       single FTP session will be used for both resource lines.

           deb ftp://ftp.debian.org/debian unstable contrib

           Types: deb
           URIs: ftp://ftp.debian.org/debian
           Suites: unstable
           Components: contrib

       Uses HTTP to access the archive at ftp.tlh.debian.org, under the
       universe directory, and uses only files found under
       unstable/binary-i386 on i386 machines, unstable/binary-amd64 on amd64,
       and so forth for other supported architectures. [Note this example only
       illustrates how to use the substitution variable; official debian
       archives are not structured like this]

           deb http://ftp.tlh.debian.org/universe unstable/binary-$(ARCH)/

           Types: deb
           URIs: http://ftp.tlh.debian.org/universe
           Suites: unstable/binary-$(ARCH)/

       Uses HTTP to get binary packages as well as sources from the stable,
       testing and unstable suites and the components main and contrib.

           deb http://deb.debian.org/debian stable main contrib
           deb-src http://deb.debian.org/debian stable main contrib
           deb http://deb.debian.org/debian testing main contrib
           deb-src http://deb.debian.org/debian testing main contrib
           deb http://deb.debian.org/debian unstable main contrib
           deb-src http://deb.debian.org/debian unstable main contrib

           Types: deb deb-src
           URIs: http://deb.debian.org/debian
           Suites: stable testing unstable
           Components: main contrib

SEE ALSO

       apt-get(8), apt.conf(5),
       /usr/share/doc/apt-doc/acquire-additional-files.txt

BUGS

       APT bug page[1]. If you wish to report a bug in APT, please see
       /usr/share/doc/debian/bug-reporting.txt or the reportbug(1) command.

AUTHORS

       Jason Gunthorpe

       APT team

NOTES

        1. APT bug page
           http://bugs.debian.org/src:apt