NAME¶
apt.conf - Configuration file for APT
DESCRIPTION¶
/etc/apt/apt.conf is the main configuration file shared by all the
tools in the APT suite of tools, though it is by no means the only place
options can be set. The suite also shares a common command line parser to
provide a uniform environment.
When an APT tool starts up it will read the configuration files in
the following order:
1.the file specified by the APT_CONFIG
environment variable (if any)
2.all files in Dir::Etc::Parts in alphanumeric ascending
order which have either no or "conf" as filename extension and which
only contain alphanumeric, hyphen (-), underscore (_) 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.
3.the main configuration file specified by
Dir::Etc::main
4.all options set in the binary specific configuration
subtree are moved into the root of the tree.
5.the command line options are applied to override the
configuration directives or to load even more configuration files.
SYNTAX¶
The configuration file is organized in a tree with options
organized into functional groups. Option specification is given with a
double colon notation; for instance APT::Get::Assume-Yes is an option within
the APT tool group, for the Get tool. Options do not inherit from their
parent groups.
Syntactically the configuration language is modeled after what the
ISC tools such as bind and dhcp use. Lines starting with // are treated as
comments (ignored), as well as all text between /* and */, just like C/C++
comments. Lines starting with # are also treated as comments. Each line is
of the form APT::Get::Assume-Yes "true";. The quotation marks and
trailing semicolon are required. The value must be on one line, and there is
no kind of string concatenation. Values must not include backslashes or
extra quotation marks. Option names are made up of alphanumeric characters
and the characters "/-:._+". A new scope can be opened with curly
braces, like this:
APT {
Get {
Assume-Yes "true";
Fix-Broken "true";
};
};
with newlines placed to make it more readable. Lists can be
created by opening a scope and including a single string enclosed in quotes
followed by a semicolon. Multiple entries can be included, separated by a
semicolon.
DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
In general the sample configuration file
/usr/share/doc/apt/examples/configure-index.gz is a good guide for how it
should look.
Case is not significant in names of configuration items, so in the
previous example you could use dpkg::pre-install-pkgs.
Names for the configuration items are optional if a list is
defined as can be seen in the DPkg::Pre-Install-Pkgs example above. If you
don't specify a name a new entry will simply add a new option to the list.
If you specify a name you can override the option in the same way as any
other option by reassigning a new value to the option.
Two special commands are defined: #include (which is deprecated
and not supported by alternative implementations) and #clear. #include will
include the given file, unless the filename ends in a slash, in which case
the whole directory is included. #clear is used to erase a part of the
configuration tree. The specified element and all its descendants are
erased. (Note that these lines also need to end with a semicolon.)
The #clear command is the only way to delete a list or a complete
scope. Reopening a scope (or using the syntax described below with an
appended ::) will not override previously written entries. Options
can only be overridden by addressing a new value to them - lists and scopes
can't be overridden, only cleared.
All of the APT tools take an -o option which allows an arbitrary
configuration directive to be specified on the command line. The syntax is a
full option name (APT::Get::Assume-Yes for instance) followed by an equals
sign then the new value of the option. To append a new element to a list,
add a trailing :: to the name of the list. (As you might suspect, the scope
syntax can't be used on the command line.)
Note that appending items to a list using :: only works for one
item per line, and that you should not use it in combination with the scope
syntax (which adds :: implicitly). Using both syntaxes together will trigger
a bug which some users unfortunately depend on: an option with the unusual
name "::" which acts like every other option with a name. This
introduces many problems; for one thing, users who write multiple lines in
this wrong syntax in the hope of appending to a list will achieve the
opposite, as only the last assignment for this option "::" will be
used. Future versions of APT will raise errors and stop working if they
encounter this misuse, so please correct such statements now while APT
doesn't explicitly complain about them.
THE APT GROUP¶
This group of options controls general APT behavior as well as
holding the options for all of the tools.
Architecture
System Architecture; sets the architecture to use when
fetching files and parsing package lists. The internal default is the
architecture apt was compiled for.
Architectures
All Architectures the system supports. For instance, CPUs
implementing the amd64 (also called x86-64) instruction set are also able to
execute binaries compiled for the i386 (x86) instruction set. This list is
used when fetching files and parsing package lists. The initial default is
always the system's native architecture (APT::Architecture), and foreign
architectures are added to the default list when they are registered via
dpkg --add-architecture.
Compressor
This scope defines which compression formats are
supported, how compression and decompression can be performed if support for
this format isn't built into apt directly and a cost-value indicating how
costly it is to compress something in this format. As an example the following
configuration stanza would allow apt to download and uncompress as well as
create and store files with the low-cost .reversed file extension which it
will pass to the command
rev without additional commandline parameters
for compression and uncompression:
APT::Compressor::rev {
Name "rev";
Extension ".reversed";
Binary "rev";
CompressArg {};
UncompressArg {};
Cost "10";
};
Build-Profiles
List of all build profiles enabled for build-dependency
resolution, without the "profile." namespace prefix. By default this
list is empty. The DEB_BUILD_PROFILES as used by
dpkg-buildpackage(1) overrides the list notation.
Default-Release
Default release to install packages from if more than one
version is available. Contains release name, codename or release version.
Examples: 'stable', 'testing', 'unstable', 'bookworm', 'trixie', '4.0',
'5.0*'. See also apt_preferences(5).
Snapshot
Snapshot to use for all repositories configured with
Snapshot: yes. See also sources.list(5), the --snapshot option
that sets this value, and Acquire::Snapshots::URI below.
Ignore-Hold
Ignore held packages; this global option causes the
problem resolver to ignore held packages in its decision making.
Clean-Installed
Defaults to on. When turned on the autoclean feature will
remove any packages which can no longer be downloaded from the cache. If
turned off then packages that are locally installed are also excluded from
cleaning - but note that APT provides no direct means to reinstall them.
Immediate-Configure
Defaults to on, which will cause APT to install essential
and important packages as soon as possible in an install/upgrade operation, in
order to limit the effect of a failing
dpkg(1) call. If this option is
disabled, APT treats an important package in the same way as an extra package:
between the unpacking of the package A and its configuration there can be many
other unpack or configuration calls for other unrelated packages B, C etc. If
these cause the
dpkg(1) call to fail (e.g. because package B's
maintainer scripts generate an error), this results in a system state in which
package A is unpacked but unconfigured - so any package depending on A is now
no longer guaranteed to work, as its dependency on A is no longer satisfied.
The immediate configuration marker is also applied in the
potentially problematic case of circular dependencies, since a dependency
with the immediate flag is equivalent to a Pre-Dependency. In theory this
allows APT to recognise a situation in which it is unable to perform
immediate configuration, abort, and suggest to the user that the option
should be temporarily deactivated in order to allow the operation to
proceed. Note the use of the word "theory" here; in the real world
this problem has rarely been encountered, in non-stable distribution
versions, and was caused by wrong dependencies of the package in question or
by a system in an already broken state; so you should not blindly disable
this option, as the scenario mentioned above is not the only problem it can
help to prevent in the first place.
Before a big operation like dist-upgrade is run with this option
disabled you should try to explicitly install the package APT is unable to
configure immediately; but please make sure you also report your problem to
your distribution and to the APT team with the bug link below, so they can
work on improving or correcting the upgrade process.
Force-LoopBreak
Never enable this option unless you really know
what you are doing. It permits APT to temporarily remove an essential package
to break a Conflicts/Conflicts or Conflicts/Pre-Depends loop between two
essential packages. Such a loop should never exist and is a grave bug.
This option will work if the essential packages are not tar,
gzip, libc, dpkg, dash or anything that those
packages depend on.
Cache-Start, Cache-Grow, Cache-Limit
APT uses since version 0.7.26 a resizable memory mapped
cache file to store the available information. Cache-Start acts as a hint of
the size the cache will grow to, and is therefore the amount of memory APT
will request at startup. The default value is 20971520 bytes (~20 MB). Note
that this amount of space needs to be available for APT; otherwise it will
likely fail ungracefully, so for memory restricted devices this value should
be lowered while on systems with a lot of configured sources it should be
increased. Cache-Grow defines in bytes with the default of 1048576 (~1 MB) how
much the cache size will be increased in the event the space defined by
Cache-Start is not enough. This value will be applied again and again until
either the cache is big enough to store all information or the size of the
cache reaches the Cache-Limit. The default of Cache-Limit is 0 which stands
for no limit. If Cache-Grow is set to 0 the automatic growth of the cache is
disabled.
Build-Essential
Defines which packages are considered essential build
dependencies.
Get
The Get subsection controls the apt-get(8) tool;
please see its documentation for more information about the options
here.
Cache
The Cache subsection controls the apt-cache(8)
tool; please see its documentation for more information about the options
here.
CDROM
The CDROM subsection controls the apt-cdrom(8)
tool; please see its documentation for more information about the options
here.
NeverAutoRemove
Never autoremove packages that match the regular
expression(s).
Protect-Kernels
This option tells apt autoremove that kernels are
protected and defaults to true. In case kernels are not protected they are
treated as any other package.
VersionedKernelPackages
Define the regular expression(s) for versioned kernel
packages. Based on these expressions a rule set is injected into apt similar
to APT::NeverAutoRemove regular expressions.
NeverAutoRemove::KernelCount
Keep a custom amount of kernels when autoremoving and
defaults to 2, meaning two kernels are kept. Apt will always keep the running
kernel and the latest one. If the latest kernel is the same as the running
kernel, the second latest kernel is kept. Because of this, any value lower
than 2 will be ignored. If you want only the latest kernel, you should set
APT::Protect-Kernels to false.
THE ACQUIRE GROUP¶
The Acquire group of options controls the download of packages as
well as the various "acquire methods" responsible for the download
itself (see also sources.list(5)).
Check-Date
Security related option defaulting to true, enabling
time-related checks. Disabling it means that the machine's time cannot be
trusted, and APT will hence disable all time-related checks, such as
Check-Valid-Until and verifying that the Date field of a release file
is not in the future.
Max-FutureTime
Maximum time (in seconds) before its creation (as
indicated by the Date header) that the Release file should be considered
valid. The default value is 10. Archive specific settings can be made by
appending the label of the archive to the option name. Preferably, the same
can be achieved for specific sources.list(5) entries by using the
Date-Max-Future option there.
Check-Valid-Until
Security related option defaulting to true, as giving a
Release file's validation an expiration date prevents replay attacks over a
long timescale, and can also for example help users to identify mirrors that
are no longer updated - but the feature depends on the correctness of the
clock on the user system. Archive maintainers are encouraged to create Release
files with the Valid-Until header, but if they don't or a stricter value is
desired the Max-ValidTime option below can be used. The
Check-Valid-Until option of sources.list(5) entries should be
preferred to disable the check selectively instead of using this global
override.
Max-ValidTime
Maximum time (in seconds) after its creation (as
indicated by the Date header) that the Release file should be considered
valid. If the Release file itself includes a Valid-Until header the earlier
date of the two is used as the expiration date. The default value is 0 which
stands for "valid forever". Archive specific settings can be made by
appending the label of the archive to the option name. Preferably, the same
can be achieved for specific sources.list(5) entries by using the
Valid-Until-Max option there.
Min-ValidTime
Minimum time (in seconds) after its creation (as
indicated by the Date header) that the Release file should be considered
valid. Use this if you need to use a seldom updated (local) mirror of a more
frequently updated archive with a Valid-Until header instead of completely
disabling the expiration date checking. Archive specific settings can and
should be used by appending the label of the archive to the option name.
Preferably, the same can be achieved for specific sources.list(5)
entries by using the Valid-Until-Min option there.
AllowTLS
Allow use of the internal TLS support in the http method.
If set to false, this completely disables support for TLS in apt's own methods
(excluding the curl-based https method). No TLS-related functions will be
called anymore.
PDiffs
Try to download deltas called PDiffs for indexes (like
Packages files) instead of downloading whole ones. True by default.
Preferably, this can be set for specific
sources.list(5) entries or
index files by using the
PDiffs option there.
Two sub-options to limit the use of PDiffs are also available:
FileLimit can be used to specify a maximum number of PDiff files should be
downloaded to update a file. SizeLimit on the other hand is the maximum
percentage of the size of all patches compared to the size of the targeted
file. If one of these limits is exceeded the complete file is downloaded
instead of the patches.
By-Hash
Try to download indexes via an URI constructed from a
hashsum of the expected file rather than downloaded via a well-known stable
filename. True by default, but automatically disabled if the source indicates
no support for it. Usage can be forced with the special value
"force". Preferably, this can be set for specific
sources.list(5) entries or index files by using the By-Hash
option there.
Queue-Mode
Queuing mode; Queue-Mode can be one of host or access
which determines how APT parallelizes outgoing connections. host means that
one connection per target host will be opened, access means that one
connection per URI type will be opened.
Retries
Number of retries to perform. If this is non-zero APT
will retry failed files the given number of times.
Source-Symlinks
Use symlinks for source archives. If set to true then
source archives will be symlinked when possible instead of copying. True is
the default.
http https
The options in these scopes configure APT's acquire
transports for the protocols HTTP and HTTPS and are documented in the
apt-transport-http(1) and apt-transport-https(1) manpages
respectively.
ftp
ftp::Proxy sets the default proxy to use for FTP URIs. It
is in the standard form of ftp://[[user][:pass]@]host[:port]/. Per host
proxies can also be specified by using the form ftp::Proxy::<host> with
the special keyword DIRECT meaning to use no proxies. If no one of the above
settings is specified,
ftp_proxy environment variable will be used. To
use an FTP proxy you will have to set the ftp::ProxyLogin script in the
configuration file. This entry specifies the commands to send to tell the
proxy server what to connect to. Please see
/usr/share/doc/apt/examples/configure-index.gz for an example of how to do
this. The substitution variables representing the corresponding URI component
are $(PROXY_USER), $(PROXY_PASS), $(SITE_USER), $(SITE_PASS), $(SITE) and
$(SITE_PORT).
The option timeout sets the timeout timer used by the method; this
value applies to the connection as well as the data timeout.
Several settings are provided to control passive mode. Generally
it is safe to leave passive mode on; it works in nearly every environment.
However, some situations require that passive mode be disabled and port mode
FTP used instead. This can be done globally or for connections that go
through a proxy or for a specific host (see the sample config file for
examples).
It is possible to proxy FTP over HTTP by setting the
ftp_proxy environment variable to an HTTP URL - see the discussion of
the http method above for syntax. You cannot set this in the configuration
file and it is not recommended to use FTP over HTTP due to its low
efficiency.
The setting ForceExtended controls the use of RFC2428 EPSV and
EPRT commands. The default is false, which means these commands are only
used if the control connection is IPv6. Setting this to true forces their
use even on IPv4 connections. Note that most FTP servers do not support
RFC2428.
cdrom
For URIs using the cdrom method, the only configurable
option is the mount point, cdrom::Mount, which must be the mount point for the
CD-ROM (or DVD, or whatever) drive as specified in /etc/fstab. It is possible
to provide alternate mount and unmount commands if your mount point cannot be
listed in the fstab. The syntax is to put
within the cdrom block. It is important to have the trailing
slash. Unmount commands can be specified using UMount.
gpgv
For GPGV URIs the only configurable option is
gpgv::Options, which passes additional parameters to gpgv.
CompressionTypes
List of compression types which are understood by the
acquire methods. Files like Packages can be available in various compression
formats. By default the acquire methods can decompress and recompress many
common formats like
xz and
gzip; with this scope the supported
formats can be queried, modified as well as support for more formats added
(see also
APT::Compressor). The syntax for this is:
Acquire::CompressionTypes::FileExtension "Methodname";
Also, the Order subgroup can be used to define in which order the
acquire system will try to download the compressed files. The acquire system
will try the first and proceed with the next compression type in this list
on error, so to prefer one over the other type simply add the preferred type
first - types not already added will be implicitly appended to the end of
the list, so e.g.
Acquire::CompressionTypes::Order:: "gz";
can be used to prefer gzip compressed files over all other
compression formats. If xz should be preferred over gzip and
bzip2 the configure setting should look like this:
Acquire::CompressionTypes::Order { "xz"; "gz"; };
It is not needed to add bz2 to the list explicitly as it will be
added automatically.
Note that the Dir::Bin::Methodname will be checked at run
time. If this option has been set and support for this format isn't directly
built into apt, the method will only be used if this file exists; e.g. for
the bzip2 method (the inbuilt) setting is:
Dir::Bin::bzip2 "/bin/bzip2";
Note also that list entries specified on the command line will be
added at the end of the list specified in the configuration files, but
before the default entries. To prefer a type in this case over the ones
specified in the configuration files you can set the option direct - not in
list style. This will not override the defined list; it will only prefix the
list with this type.
The special type uncompressed can be used to give uncompressed
files a preference, but note that most archives don't provide uncompressed
files so this is mostly only usable for local mirrors.
GzipIndexes
When downloading gzip compressed indexes (Packages,
Sources, or Translations), keep them gzip compressed locally instead of
unpacking them. This saves quite a lot of disk space at the expense of more
CPU requirements when building the local package caches. False by
default.
Languages
The Languages subsection controls which Translation files
are downloaded and in which order APT tries to display the
description-translations. APT will try to display the first available
description in the language which is listed first. Languages can be defined
with their short or long language codes. Note that not all archives provide
Translation files for every language - the long language codes are especially
rare.
The default list includes "environment" and
"en". "environment" has a special meaning here: it will
be replaced at runtime with the language codes extracted from the
LC_MESSAGES environment variable. It will also ensure that these codes are
not included twice in the list. If LC_MESSAGES is set to "C" only
the Translation-en file (if available) will be used. To force APT to use no
Translation file use the setting Acquire::Languages=none. "none"
is another special meaning code which will stop the search for a suitable
Translation file. This tells APT to download these translations too, without
actually using them unless the environment specifies the languages. So the
following example configuration will result in the order "en, de"
in an English locale or "de, en" in a German one. Note that
"fr" is downloaded, but not used unless APT is used in a French
locale (where the order would be "fr, de, en").
Acquire::Languages { "environment"; "de"; "en"; "none"; "fr"; };
Note: To prevent problems resulting from APT being executed in
different environments (e.g. by different users or by other programs) all
Translation files which are found in /var/lib/apt/lists/ will be added to
the end of the list (after an implicit "none").
ForceIPv4
When downloading, force to use only the IPv4
protocol.
ForceIPv6
When downloading, force to use only the IPv6
protocol.
MaxReleaseFileSize
The maximum file size of Release/Release.gpg/InRelease
files. The default is 10MB.
EnableSrvRecords
This option controls if apt will use the DNS SRV server
record as specified in RFC 2782 to select an alternative server to connect to.
The default is "true".
AllowInsecureRepositories
Allow update operations to load data files from
repositories without sufficient security information. The default value is
"false". Concept, implications as well as alternatives are detailed
in apt-secure(8).
AllowWeakRepositories
Allow update operations to load data files from
repositories which provide security information, but these are deemed no
longer cryptographically strong enough. The default value is
"false". Concept, implications as well as alternatives are detailed
in apt-secure(8).
AllowDowngradeToInsecureRepositories
Allow that a repository that was previously gpg signed to
become unsigned during an update operation. When there is no valid signature
for a previously trusted repository apt will refuse the update. This option
can be used to override this protection. You almost certainly never want to
enable this. The default is false. Concept, implications as well as
alternatives are detailed in apt-secure(8).
Changelogs::URI scope
Acquiring changelogs can only be done if an URI is known
from where to get them. Preferable the Release file indicates this in a
'Changelogs' field. If this isn't available the Label/Origin field of the
Release file is used to check if a
Acquire::Changelogs::URI::Label::LABEL or
Acquire::Changelogs::URI::Origin::ORIGIN option exists and if so this
value is taken. The value in the Release file can be overridden with
Acquire::Changelogs::URI::Override::Label::LABEL or
Acquire::Changelogs::URI::Override::Origin::ORIGIN. The value should be
a normal URI to a text file, except that package specific data is replaced
with the placeholder @CHANGEPATH@. The value for it is: 1. if the package is
from a component (e.g. main) this is the first part otherwise it is omitted,
2. the first letter of source package name, except if the source package name
starts with 'lib' in which case it will be the first four letters. 3. The
complete source package name. 4. the complete name again and 5. the source
version. The first (if present), second, third and fourth part are separated
by a slash ('/') and between the fourth and fifth part is an underscore ('_').
The special value 'no' is available for this option indicating that this
source can't be used to acquire changelog files from. Another source will be
tried if available in this case.
Snapshots::URI scope
Like changelogs, snapshots can only be acquired if an URI
is known from where to get them. Preferable the Release file indicates this in
a 'Snapshots' field. If this isn't available the Label/Origin field of the
Release file is used to check if a
Acquire::Snapshots::URI::Label::LABEL or
Acquire::Snapshots::URI::Origin::ORIGIN option exists and if so this
value is taken. The value in the Release file can be overridden with
Acquire::Snapshots::URI::Override::Label::LABEL or
Acquire::Snapshots::URI::Override::Origin::ORIGIN. The value should be
a normal URI to a directory, except that the snapshot ID replaced with the
placeholder @SNAPSHOTID. The special value 'no' is available for this option
indicating that this source cannot be used to acquire snapshots from. Another
source will be tried if available in this case.
BINARY SPECIFIC CONFIGURATION¶
Especially with the introduction of the apt binary it can
be useful to set certain options only for a specific binary as even options
which look like they would effect only a certain binary like
APT::Get::Show-Versions effect apt-get as well as
apt.
Setting an option for a specific binary only can be achieved by
setting the option inside the Binary::specific-binary
scope. Setting the option APT::Get::Show-Versions for the apt
only can e.g. by done by setting Binary::apt::APT::Get::Show-Versions
instead.
Note that as seen in the DESCRIPTION section further above you
can't set binary-specific options on the commandline itself nor in
configuration files loaded via the commandline.
DIRECTORIES¶
The Dir::State section has directories that pertain to local state
information. lists is the directory to place downloaded package lists in and
status is the name of the dpkg(1) status file. preferences is the
name of the APT preferences file. Dir::State contains the default directory
to prefix on all sub-items if they do not start with / or ./.
Dir::Cache contains locations pertaining to local cache
information, such as the two package caches srcpkgcache and pkgcache as well
as the location to place downloaded archives, Dir::Cache::archives.
Generation of caches can be turned off by setting pkgcache or srcpkgcache to
"". This will slow down startup but save disk space. It is
probably preferable to turn off the pkgcache rather than the srcpkgcache.
Like Dir::State the default directory is contained in Dir::Cache
Dir::Etc contains the location of configuration files, sourcelist
gives the location of the sourcelist and main is the default configuration
file (setting has no effect, unless it is done from the config file
specified by APT_CONFIG).
The Dir::Parts setting reads in all the config fragments in
lexical order from the directory specified. After this is done then the main
config file is loaded.
Binary programs are pointed to by Dir::Bin. Dir::Bin::Methods
specifies the location of the method handlers and gzip, bzip2, lzma, dpkg,
apt-get dpkg-source dpkg-buildpackage and apt-cache specify the location of
the respective programs.
The configuration item RootDir has a special meaning. If set, all
paths will be relative to RootDir, even paths that are specified
absolutely. So, for instance, if RootDir is set to /tmp/staging and
Dir::State::status is set to /var/lib/dpkg/status, then the status file will
be looked up in /tmp/staging/var/lib/dpkg/status. If you want to prefix only
relative paths, set Dir instead.
The Ignore-Files-Silently list can be used to specify which files
APT should silently ignore while parsing the files in the fragment
directories. Per default a file which ends with .disabled, ~, .bak or
.dpkg-[a-z]+ is silently ignored. As seen in the last default value these
patterns can use regular expression syntax.
APT IN DSELECT¶
When APT is used as a dselect(1) method several
configuration directives control the default behavior. These are in the
DSelect section.
Clean
Cache Clean mode; this value may be one of always,
prompt, auto, pre-auto and never. always and prompt will remove all packages
from the cache after upgrading, prompt (the default) does so conditionally.
auto removes only those packages which are no longer downloadable (replaced
with a new version for instance). pre-auto performs this action before
downloading new packages.
options
The contents of this variable are passed to
apt-get(8) as command line options when it is run for the install
phase.
Updateoptions
The contents of this variable are passed to
apt-get(8) as command line options when it is run for the update
phase.
PromptAfterUpdate
If true the [U]pdate operation in dselect(1) will
always prompt to continue. The default is to prompt only on error.
HOW APT CALLS DPKG(1)¶
Several configuration directives control how APT invokes
dpkg(1). These are in the DPkg section.
options
This is a list of options to pass to dpkg(1). The
options must be specified using the list notation and each list item is passed
as a single argument to dpkg(1).
Path
This is a string that defines the PATH environment
variable used when running dpkg. It may be set to any valid value of that
environment variable; or the empty string, in which case the variable is not
changed.
Pre-Invoke, Post-Invoke
This is a list of shell commands to run before/after
invoking dpkg(1). Like options this must be specified in list notation.
The commands are invoked in order using /bin/sh; should any fail APT will
abort.
Pre-Install-Pkgs
This is a list of shell commands to run before invoking
dpkg(1). Like options this must be specified in list notation. The
commands are invoked in order using /bin/sh; should any fail APT will abort.
APT will pass the filenames of all .deb files it is going to install to the
commands, one per line on the requested file descriptor, defaulting to
standard input.
Version 2 of this protocol sends more information through the
requested file descriptor: a line with the text VERSION 2, the APT
configuration space, and a list of package actions with filename and version
information.
Each configuration directive line has the form key=value. Special
characters (equal signs, newlines, nonprintable characters, quotation marks,
and percent signs in key and newlines, nonprintable characters, and percent
signs in value) are %-encoded. Lists are represented by multiple key::=value
lines with the same key. The configuration section ends with a blank
line.
Package action lines consist of five fields in Version 2: package
name (without architecture qualification even if foreign), old version,
direction of version change (< for upgrades, > for downgrades, = for
no change), new version, action. The version fields are "-" for no
version at all (for example when installing a package for the first time; no
version is treated as earlier than any real version, so that is an upgrade,
indicated as - < 1.23.4). The action field is "**CONFIGURE**"
if the package is being configured, "**REMOVE**" if it is being
removed, or the filename of a .deb file if it is being unpacked.
In Version 3 after each version field follows the architecture of
this version, which is "-" if there is no version, and a field
showing the MultiArch type "same", "foreign",
"allowed" or "none". Note that "none" is an
incorrect typename which is just kept to remain compatible, it should be
read as "no" and users are encouraged to support both.
The version of the protocol to be used for the command cmd
can be chosen by setting DPkg::Tools::options::cmd::Version
accordingly, the default being version 1. If APT isn't supporting the
requested version it will send the information in the highest version it has
support for instead.
The file descriptor to be used to send the information can be
requested with DPkg::Tools::options::cmd::InfoFD which defaults to 0
for standard input and is available since version 0.9.11. Support for the
option can be detected by looking for the environment variable
APT_HOOK_INFO_FD which contains the number of the used file
descriptor as a confirmation.
Run-Directory
APT chdirs to this directory before invoking
dpkg(1), the default is /.
Build-options
These options are passed to dpkg-buildpackage(1)
when compiling packages; the default is to disable signing and produce all
binaries.
DPkg::ConfigurePending
If this option is set APT will call dpkg --configure
--pending to let dpkg(1) handle all required configurations and
triggers. This option is activated by default, but deactivating it could be
useful if you want to run APT multiple times in a row - e.g. in an installer.
In this scenario you could deactivate this option in all but the last
run.
PERIODIC AND ARCHIVES OPTIONS¶
APT::Periodic and APT::Archives groups of options configure
behavior of apt periodic updates, which is done by the
/usr/lib/apt/apt.systemd.daily script. See the top of this script for the
brief documentation of these options.
DEBUG OPTIONS¶
Enabling options in the Debug:: section will cause debugging
information to be sent to the standard error stream of the program utilizing
the apt libraries, or enable special program modes that are primarily useful
for debugging the behavior of apt. Most of these options are not interesting
to a normal user, but a few may be:
•Debug::pkgProblemResolver enables output about
the decisions made by dist-upgrade, upgrade, install, remove, purge.
•Debug::NoLocking disables all file locking. This
can be used to run some operations (for instance, apt-get -s install) as a
non-root user.
•Debug::pkgDPkgPM prints out the actual command
line each time that apt invokes dpkg(1).
•Debug::IdentCdrom disables the inclusion of
statfs data in CD-ROM IDs.
A full list of debugging options to apt follows.
Debug::Acquire::cdrom
Print information related to accessing
cdrom://
sources.
Debug::Acquire::ftp
Print information related to downloading packages using
FTP.
Debug::Acquire::http
Print information related to downloading packages using
HTTP.
Debug::Acquire::https
Print information related to downloading packages using
HTTPS.
Debug::Acquire::gpgv
Print information related to verifying cryptographic
signatures using gpg.
Debug::aptcdrom
Output information about the process of accessing
collections of packages stored on CD-ROMs.
Debug::BuildDeps
Describes the process of resolving build-dependencies in
apt-get(8).
Debug::Hashes
Output each cryptographic hash that is generated by the
apt libraries.
Debug::IdentCDROM
Do not include information from statfs, namely the number
of used and free blocks on the CD-ROM filesystem, when generating an ID for a
CD-ROM.
Debug::NoLocking
Disable all file locking. For instance, this will allow
two instances of “apt-get update” to run at the same time.
Debug::pkgAcquire
Log when items are added to or removed from the global
download queue.
Debug::pkgAcquire::Auth
Output status messages and errors related to verifying
checksums and cryptographic signatures of downloaded files.
Debug::pkgAcquire::Diffs
Output information about downloading and applying package
index list diffs, and errors relating to package index list diffs.
Debug::pkgAcquire::RRed
Output information related to patching apt package lists
when downloading index diffs instead of full indices.
Debug::pkgAcquire::Worker
Log all interactions with the sub-processes that actually
perform downloads.
Debug::pkgAutoRemove
Log events related to the automatically-installed status
of packages and to the removal of unused packages.
Debug::pkgDepCache::AutoInstall
Generate debug messages describing which packages are
being automatically installed to resolve dependencies. This corresponds to the
initial auto-install pass performed in, e.g., apt-get install, and not to the
full apt dependency resolver; see Debug::pkgProblemResolver for that.
Debug::pkgDepCache::Marker
Generate debug messages describing which packages are
marked as keep/install/remove while the ProblemResolver does his work. Each
addition or deletion may trigger additional actions; they are shown indented
two additional spaces under the original entry. The format for each line is
MarkKeep, MarkDelete or MarkInstall followed by package-name <a.b.c ->
d.e.f | x.y.z> (section) where a.b.c is the current version of the package,
d.e.f is the version considered for installation and x.y.z is a newer version,
but not considered for installation (because of a low pin score). The later
two can be omitted if there is none or if it is the same as the installed
version. section is the name of the section the package appears in.
Debug::pkgDPkgPM
When invoking dpkg(1), output the precise command
line with which it is being invoked, with arguments separated by a single
space character.
Debug::pkgDPkgProgressReporting
Output all the data received from dpkg(1) on the
status file descriptor and any errors encountered while parsing it.
Debug::pkgOrderList
Generate a trace of the algorithm that decides the order
in which apt should pass packages to dpkg(1).
Debug::pkgPackageManager
Output status messages tracing the steps performed when
invoking dpkg(1).
Debug::pkgPolicy
Output the priority of each package list on
startup.
Debug::pkgProblemResolver
Trace the execution of the dependency resolver (this
applies only to what happens when a complex dependency problem is
encountered).
Debug::pkgProblemResolver::ShowScores
Display a list of all installed packages with their
calculated score used by the pkgProblemResolver. The description of the
package is the same as described in Debug::pkgDepCache::Marker
Debug::sourceList
Print information about the vendors read from
/etc/apt/vendors.list.
Debug::RunScripts
Display the external commands that are called by apt
hooks. This includes e.g. the config options DPkg::{Pre,Post}-Invoke or
APT::Update::{Pre,Post}-Invoke.
EXAMPLES¶
/usr/share/doc/apt/examples/configure-index.gz is a configuration
file showing example values for all possible options.
FILES¶
/etc/apt/apt.conf
APT configuration file. Configuration Item:
Dir::Etc::Main.
/etc/apt/apt.conf.d/
APT configuration file fragments. Configuration Item:
Dir::Etc::Parts.
SEE ALSO¶
apt-cache(8), apt-config(8),
apt_preferences(5).
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
Daniel Burrows <dburrows@debian.org>
Initial documentation of Debug::*.
