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APT.CONF(5)			      APT			   APT.CONF(5)

       apt.conf - Configuration file for APT

       /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. the command line options are applied to override the configuration
	   directives or to load even more configuration files.

       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. 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

       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.

       This group of options controls general APT behavior as well as holding
       the options for all of the tools.

	   System Architecture; sets the architecture to use when fetching
	   files and parsing package lists. The internal default is the
	   architecture apt was compiled for.

	   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

	   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 to install packages from if more than one version
	   is available. Contains release name, codename or release version.
	   Examples: 'stable', 'testing', 'unstable', 'wheezy', 'jessie',
	   '4.0', '5.0*'. See also apt_preferences(5).

	   Ignore held packages; this global option causes the problem
	   resolver to ignore held packages in its decision making.

	   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.

	   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 buglink below, so they can work on improving or correcting the
	   upgrade process.

	   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

	   Defines which packages are considered essential build dependencies.

	   The Get subsection controls the apt-get(8) tool; please see its
	   documentation for more information about the options here.

	   The Cache subsection controls the apt-cache(8) tool; please see its
	   documentation for more information about the options here.

	   The CDROM subsection controls the apt-cdrom(8) tool; please see its
	   documentation for more information about the options here.

       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)).

	   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.

	   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

	   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.

	   Try to download deltas called PDiffs for indexes (like Packages
	   files) instead of downloading whole ones. True by default.

	   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.

	   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.

	   Number of retries to perform. If this is non-zero APT will retry
	   failed files the given number of times.

	   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::Proxy sets the default proxy to use for HTTP URIs. It is in
	   the standard form of http://[[user][:pass]@]host[:port]/. Per host
	   proxies can also be specified by using the form http::Proxy::<host>
	   with the special keyword DIRECT meaning to use no proxies. If no
	   one of the above settings is specified, http_proxy environment
	   variable will be used.

	   Three settings are provided for cache control with HTTP/1.1
	   compliant proxy caches.  No-Cache tells the proxy not to use its
	   cached response under any circumstances.  Max-Age sets the allowed
	   maximum age (in seconds) of an index file in the cache of the
	   proxy.  No-Store specifies that the proxy should not store the
	   requested archive files in its cache, which can be used to prevent
	   the proxy from polluting its cache with (big) .deb files.

	   The option timeout sets the timeout timer used by the method; this
	   value applies to the connection as well as the data timeout.

	   The setting Acquire::http::Pipeline-Depth can be used to enable
	   HTTP pipelining (RFC 2616 section which can be beneficial
	   e.g. on high-latency connections. It specifies how many requests
	   are sent in a pipeline. Previous APT versions had a default of 10
	   for this setting, but the default value is now 0 (= disabled) to
	   avoid problems with the ever-growing amount of webservers and
	   proxies which choose to not conform to the HTTP/1.1 specification.

	   Acquire::http::AllowRedirect controls whether APT will follow
	   redirects, which is enabled by default.

	   The used bandwidth can be limited with Acquire::http::Dl-Limit
	   which accepts integer values in kilobytes per second. The default
	   value is 0 which deactivates the limit and tries to use all
	   available bandwidth. Note that this option implicitly disables
	   downloading from multiple servers at the same time.

	   Acquire::http::User-Agent can be used to set a different User-Agent
	   for the http download method as some proxies allow access for
	   clients only if the client uses a known identifier.

	   Acquire::http::Proxy-Auto-Detect can be used to specify an external
	   command to discover the http proxy to use. Apt expects the command
	   to output the proxy on stdout in the style http://proxy:port/. This
	   will override the generic Acquire::http::Proxy but not any specific
	   host proxy configuration set via Acquire::http::Proxy::$HOST. See
	   the squid-deb-proxy-client(1) package for an example implementation
	   that uses avahi. This option takes precedence over the legacy
	   option name ProxyAutoDetect.

	   The Cache-control, Timeout, AllowRedirect, Dl-Limit and proxy
	   options work for HTTPS URIs in the same way as for the http method,
	   and default to the same values if they are not explicitly set. The
	   Pipeline-Depth option is not yet supported.

	   CaInfo suboption specifies place of file that holds info about
	   trusted certificates.  <host>::CaInfo is the corresponding per-host
	   option.  Verify-Peer boolean suboption determines whether or not
	   the server's host certificate should be verified against trusted
	   certificates.  <host>::Verify-Peer is the corresponding per-host
	   option.  Verify-Host boolean suboption determines whether or not
	   the server's hostname should be verified.  <host>::Verify-Host is
	   the corresponding per-host option.  SslCert determines what
	   certificate to use for client authentication.  <host>::SslCert is
	   the corresponding per-host option.  SslKey determines what private
	   key to use for client authentication.  <host>::SslKey is the
	   corresponding per-host option.  SslForceVersion overrides default
	   SSL version to use. It can contain either of the strings 'TLSv1' or
	   'SSLv3'.  <host>::SslForceVersion is the corresponding per-host

	   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.

	   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

	       /cdrom/::Mount "foo";

	   within the cdrom block. It is important to have the trailing slash.
	   Unmount commands can be specified using UMount.

	   For GPGV URIs the only configurable option is gpgv::Options, which
	   passes additional parameters to gpgv.

	   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
	   bzip2, lzma and gzip compressed files; with this setting more
	   formats can be added on the fly or the used method can be changed.
	   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 - default 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 bzip2 and lzma. If
	   lzma should be preferred over gzip and bzip2 the configure setting
	   should look like this:

	       Acquire::CompressionTypes::Order { "lzma"; "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, 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 useable for local

	   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.

	   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").

	   When downloading, force to use only the IPv4 protocol.

	   When downloading, force to use only the IPv6 protocol.

       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 their names to the empty string.
       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-getdpkg-sourcedpkg-buildpackage and apt-cache specify the
       location of the respective programs.

       The configuration item RootDir has a special meaning. If set, all paths
       in Dir:: 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.

       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 end with .disabled, ~, .bak or
       .dpkg-[a-z]+ is silently ignored. As seen in the last default value
       these patterns can use regular expression syntax.

       When APT is used as a dselect(1) method several configuration
       directives control the default behavior. These are in the DSelect

	   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.

	   The contents of this variable are passed to apt-get(8) as command
	   line options when it is run for the install phase.

	   The contents of this variable are passed to apt-get(8) as command
	   line options when it is run for the update phase.

	   If true the [U]pdate operation in dselect(1) will always prompt to
	   continue. The default is to prompt only on error.

       Several configuration directives control how APT invokes dpkg(1). These
       are in the DPkg section.

	   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).

       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.

	   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 dumps more information, including the
	   protocol version, the APT configuration space and the packages,
	   files and versions being changed. Version 3 adds the architecture
	   and MultiArch flag to each version being dumped.

	   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.

	   APT chdirs to this directory before invoking dpkg(1), the default
	   is /.

	   These options are passed to dpkg-buildpackage(1) when compiling
	   packages; the default is to disable signing and produce all

   dpkg trigger usage (and related options)
       APT can call dpkg(1) in such a way as to let it make aggressive use of
       triggers over multiple calls of dpkg(1). Without further options
       dpkg(1) will use triggers once each time it runs. Activating these
       options can therefore decrease the time needed to perform the install
       or upgrade. Note that it is intended to activate these options per
       default in the future, but as it drastically changes the way APT calls
       dpkg(1) it needs a lot more testing.  These options are therefore
       currently experimental and should not be used in production
       environments.  It also breaks progress reporting such that all
       front-ends will currently stay around half (or more) of the time in the
       100% state while it actually configures all packages.

       Note that it is not guaranteed that APT will support these options or
       that these options will not cause (big) trouble in the future. If you
       have understand the current risks and problems with these options, but
       are brave enough to help testing them, create a new configuration file
       and test a combination of options. Please report any bugs, problems and
       improvements you encounter and make sure to note which options you have
       used in your reports. Asking dpkg(1) for help could also be useful for
       debugging proposes, see e.g.  dpkg --audit. A defensive option
       combination would be

	   DPkg::NoTriggers "true";
	   PackageManager::Configure "smart";
	   DPkg::ConfigurePending "true";
	   DPkg::TriggersPending "true";

	   Add the no triggers flag to all dpkg(1) calls (except the
	   ConfigurePending call). See dpkg(1) if you are interested in what
	   this actually means. In short: dpkg(1) will not run the triggers
	   when this flag is present unless it is explicitly called to do so
	   in an extra call. Note that this option exists (undocumented) also
	   in older APT versions with a slightly different meaning: Previously
	   these option only append --no-triggers to the configure calls to
	   dpkg(1) - now APT will also add this flag to the unpack and remove

	   Valid values are "all", "smart" and "no". The default value is
	   "all", which causes APT to configure all packages. The "smart" way
	   is to configure only packages which need to be configured before
	   another package can be unpacked (Pre-Depends), and let the rest be
	   configured by dpkg(1) with a call generated by the ConfigurePending
	   option (see below). On the other hand, "no" will not configure
	   anything, and totally relies on dpkg(1) for configuration (which at
	   the moment will fail if a Pre-Depends is encountered). Setting this
	   option to any value other than all will implicitly also activate
	   the next option by default, as otherwise the system could end in an
	   unconfigured and potentially unbootable state.

	   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 automatically per default if the previous
	   option is not set to all, but deactivating it could be useful if
	   you want to run APT multiple times in a row - e.g. in an installer.
	   In these sceneries you could deactivate this option in all but the
	   last run.

	   Useful for the smart configuration as a package which has pending
	   triggers is not considered as installed, and dpkg(1) treats them as
	   unpacked currently which is a showstopper for Pre-Dependencies (see
	   debbugs #526774). Note that this will process all triggers, not
	   only the triggers needed to configure this package.

	   Essential packages (and their dependencies) should be configured
	   immediately after unpacking. It is a good idea to do this quite
	   early in the upgrade process as these configure calls also
	   currently require DPkg::TriggersPending which will run quite a few
	   triggers (which may not be needed). Essentials get per default a
	   high score but the immediate flag is relatively low (a package
	   which has a Pre-Depends is rated higher). These option and the
	   others in the same group can be used to change the scoring. The
	   following example shows the settings with their default values.

	       OrderList::Score {
		    Delete 500;
		    Essential 200;
		    Immediate 10;
		    PreDepends 50;

       APT::Periodic and APT::Archives groups of options configure behavior of
       apt periodic updates, which is done by the /etc/cron.daily/apt script.
       See the top of this script for the brief documentation of these

       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

       ·   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

       A full list of debugging options to apt follows.

	   Print information related to accessing cdrom:// sources.

	   Print information related to downloading packages using FTP.

	   Print information related to downloading packages using HTTP.

	   Print information related to downloading packages using HTTPS.

	   Print information related to verifying cryptographic signatures
	   using gpg.

	   Output information about the process of accessing collections of
	   packages stored on CD-ROMs.

	   Describes the process of resolving build-dependencies in apt-

	   Output each cryptographic hash that is generated by the apt

	   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.

	   Disable all file locking. For instance, this will allow two
	   instances of “apt-get update” to run at the same time.

	   Log when items are added to or removed from the global download

	   Output status messages and errors related to verifying checksums
	   and cryptographic signatures of downloaded files.

	   Output information about downloading and applying package index
	   list diffs, and errors relating to package index list diffs.

	   Output information related to patching apt package lists when
	   downloading index diffs instead of full indices.

	   Log all interactions with the sub-processes that actually perform

	   Log events related to the automatically-installed status of
	   packages and to the removal of unused packages.

	   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.

	   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

	   When invoking dpkg(1), output the precise command line with which
	   it is being invoked, with arguments separated by a single space

	   Output all the data received from dpkg(1) on the status file
	   descriptor and any errors encountered while parsing it.

	   Generate a trace of the algorithm that decides the order in which
	   apt should pass packages to dpkg(1).

	   Output status messages tracing the steps performed when invoking

	   Output the priority of each package list on startup.

	   Trace the execution of the dependency resolver (this applies only
	   to what happens when a complex dependency problem is encountered).

	   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

	   Print information about the vendors read from

	   Display the external commands that are called by apt hooks. This
	   includes e.g. the config options DPkg::{Pre,Post}-Invoke or

       /usr/share/doc/apt/examples/configure-index.gz is a configuration file
       showing example values for all possible options.

	   APT configuration file. Configuration Item: Dir::Etc::Main.

	   APT configuration file fragments. Configuration Item:

       apt-cache(8), apt-config(8), apt_preferences(5).

       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.

       Jason Gunthorpe

       APT team

       Daniel Burrows <dburrows@debian.org>
	   Initial documentation of Debug::*.

	1. APT bug page

APT 1.0.1ubuntu2		 09 June 2012			   APT.CONF(5)

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