SOURCES.LIST(5) APT SOURCES.LIST(5)NAMEsources.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://deb.debian.org/debian stretch main contrib non-free
deb http://security.debian.org stretch/updates main contrib non-free
or like this in deb822 style format:
Types: deb
URIs: http://deb.debian.org/debian
Suites: stretch
Components: main contrib non-free
Types: deb
URIs: http://security.debian.org
Suites: stretch/updates
Components: main contrib non-free
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.
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 ALSOapt-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
APT 1.6~alpha6 22 November 2017 SOURCES.LIST(5)
