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

NAME
       apt.conf - Configuration file for APT

DESCRIPTION
       apt.conf is the main configuration file for the APT suite of tools, but
       by far not the only place changes to options can be made. All tools
       therefore share the configuration files and also use 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 no or "conf" as filename extension and which only contain
	   alphanumeric, hyphen (-), underscore (_) and period (.) characters
	   - otherwise they 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.

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. Each line is of the form APT::Get::Assume-Yes "true";.
       The trailing semicolon and the quotes are required. The value must be
       on one line, and there is no kind of string concatenation. It must not
       include inside quotes. The behavior of the backslash "\" and escaped
       characters inside a value is undefined and it should not be used. An
       option name may include alphanumerical characters and the "/-:._+"
       characters. A new scope can be opened with curly braces, like:

	   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, each
       separated by a semicolon.

	   DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};

       In general the sample configuration file in
       /usr/share/doc/apt/examples/apt.conf
       /usr/share/doc/apt/examples/configure-index.gz is a good guide for how
       it should look.

       The names of the configuration items are not case-sensitive. 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
       it can be see 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 as every other option by
       reassigning a new value to the option.

       Two specials are allowed, #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, then 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 the ::-style described below will not
       override previously written entries. Only options can be overridden by
       addressing a new value to it - lists and scopes can't be overridden,
       only cleared.

       All of the APT tools take a -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. Lists can be appended
       too by adding a trailing :: to the list name. (As you might suspect:
       The scope syntax can't be used on the command line.)

       Note that you can use :: only for appending one item per line to a list
       and that you should not use it in combination with the scope syntax.
       (The scope syntax implicit insert ::) Using both syntaxes together will
       trigger a bug which some users unfortunately relay on: An option with
       the unusual name "::" which acts like every other option with a name.
       These introduces many problems including that a user who writes
       multiple lines in this wrong syntax in the hope to append to a list
       will gain the opposite as only the last assignment for this option "::"
       will be used. Upcoming APT versions will raise errors and will stop
       working if they encounter this misuse, so please correct such
       statements now as long as APT doesn't complain explicit 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.

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

       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 fast as possible in the install/upgrade
	   operation. This is done to limit the effect of a failing dpkg(1)
	   call: If this option is disabled APT does treat an important
	   package in the same way as an extra package: Between the unpacking
	   of the important package A and his configuration can then be many
	   other unpack or configuration calls, e.g. for package B which has
	   no relation to A, but causes the dpkg call to fail (e.g. because
	   maintainer script of package B generates an error) which results in
	   a system state in which package A is unpacked but unconfigured -
	   each package depending on A is now no longer guaranteed to work as
	   their dependency on A is not longer satisfied. The immediate
	   configuration marker is also applied to all dependencies which can
	   generate a problem if the dependencies e.g. form a circle as a
	   dependency with the immediate flag is comparable with a
	   Pre-Dependency. So in theory it is possible that APT encounters a
	   situation in which it is unable to perform immediate configuration,
	   errors out and refers to this option so the user can deactivate the
	   immediate configuration temporarily to be able to perform an
	   install/upgrade again. Note the use of the word "theory" here as
	   this problem was only encountered by now in real world a few times
	   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 mentioned scenario above is not the only problem immediate
	   configuration can help to prevent in the first place. Before a big
	   operation like dist-upgrade is run with this option disabled it
	   should be tried to explicitly install the package APT is unable to
	   configure immediately, but please make sure to report your problem
	   also to your distribution and to the APT team with the buglink
	   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-Depend 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, bash or anything that those packages depend
	   on.

       Cache-Start, Cache-Grow and 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
	   to which size the Cache will grow and is therefore the amount of
	   memory APT will request at startup. The default value is 20971520
	   bytes (~20 MB). Note that these amount of space need to be
	   available for APT otherwise it will likely fail ungracefully, so
	   for memory restricted devices these value should be lowered while
	   on systems with a lot of configured sources this might be
	   increased.  Cache-Grow defines in byte 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. These 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 grow of the cache is
	   disabled.

       Build-Essential
	   Defines which package(s) 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.

THE ACQUIRE GROUP
       The Acquire group of options controls the download of packages and the
       URI handlers.

       Check-Valid-Until
	   Security related option defaulting to true as an expiring
	   validation for a Release file prevents longtime replay attacks and
	   can e.g. also help users to identify no longer updated mirrors -
	   but the feature depends on the correctness of the time 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 volitional the following Max-ValidTime option can be used.

       Max-ValidTime
	   Seconds the Release file should be considered valid after it was
	   created. The default is "for ever" (0) if the Release file of the
	   archive doesn't include a Valid-Until header. If it does then this
	   date is the default. The date from the Release file or the date
	   specified by the creation time of the Release file (Date header)
	   plus the seconds specified with this options are used to check if
	   the validation of a file has expired by using the earlier date of
	   the two. Archive specific settings can be made by appending the
	   label of the archive to the option name.

       PDiffs
	   Try to download deltas called PDiffs for Packages or Sources files
	   instead of downloading whole ones. True by default.

	   Two sub-options to limit the use of PDiffs are also available: With
	   FileLimit can be specified how many PDiff files are downloaded at
	   most to patch a file.  SizeLimit on the other hand is the maximum
	   precentage 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.

       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
	   HTTP URIs; http::Proxy is the default http proxy to use. 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 to not use its
	   cached response under any circumstances, Max-Age is sent only for
	   index files and tells the cache to refresh its object if it is
	   older than the given number of seconds. Debian updates its index
	   files daily so the default is 1 day.	 No-Store specifies that the
	   cache should never store this request, it is only set for archive
	   files. This may be useful to prevent polluting a proxy cache with
	   very large .deb files. Note: Squid 2.0.2 does not support any of
	   these options.

	   The option timeout sets the timeout timer used by the method, this
	   applies to all things including connection timeout and data
	   timeout.

	   One setting is provided to control the pipeline depth in cases
	   where the remote server is not RFC conforming or buggy (such as
	   Squid 2.0.2).  Acquire::http::Pipeline-Depth can be a value from 0
	   to 5 indicating how many outstanding requests APT should send. A
	   value of zero MUST be specified if the remote host does not
	   properly linger on TCP connections - otherwise data corruption will
	   occur. Hosts which require this are in violation of RFC 2068.

	   The used bandwidth can be limited with Acquire::http::Dl-Limit
	   which accepts integer values in kilobyte. The default value is 0
	   which deactivates the limit and tries uses as much as possible of
	   the bandwidth (Note that this option implicit deactivates the
	   download 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.

       https
	   HTTPS URIs. Cache-control, Timeout, AllowRedirect, Dl-Limit and
	   proxy options are the same as for http method and will also default
	   to the options from the http method if they are not explicitly set
	   for https.  Pipeline-Depth option is not supported yet.

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

       ftp
	   FTP URIs; ftp::Proxy is the default ftp proxy to use. 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 a 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 available are
	   $(PROXY_USER) $(PROXY_PASS) $(SITE_USER) $(SITE_PASS) $(SITE) and
	   $(SITE_PORT) Each is taken from it's respective URI component.

	   The option timeout sets the timeout timer used by the method, this
	   applies to all things including connection timeout and 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,
	   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 a 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
	   CDROM URIs; the only setting for CDROM URIs is the mount point,
	   cdrom::Mount which must be the mount point for the CDROM 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 (such as an SMB mount and old mount packages). The syntax is
	   to put

	       /cdrom/::Mount "foo";

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

       gpgv
	   GPGV URIs; the only option for GPGV URIs is the option to pass
	   additional parameters to gpgv.  gpgv::Options Additional options
	   passed to gpgv.

       CompressionTypes
	   List of compression types which are understood by the acquire
	   methods. Files like Packages can be available in various
	   compression formats. Per 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 simple add the preferred type at first - not already
	   added default types will be added at run time 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 explicit to the list as it will be
	   added automatic.

	   Note that at run time the Dir::Bin::Methodname will be checked: If
	   this setting exists 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 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.

	   While it is possible to add an empty compression type to the order
	   list, but APT in its current version doesn't understand it
	   correctly and will display many warnings about not downloaded files
	   - these warnings are most of the time false negatives. Future
	   versions will maybe include a way to really prefer uncompressed
	   files to support the usage of 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 at first.
	   Languages can be defined with their short or long Languagecodes.
	   Note that not all archives provide Translation files for every
	   Language - especially the long Languagecodes are rare, so please
	   inform you which ones are available before you set here impossible
	   values.

	   The default list includes "environment" and "en". "environment" has
	   a special meaning here: It will be replaced at runtime with the
	   languagecodes 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 fitting Translation
	   file. This can be used by the system administrator to let APT know
	   that it should download also this files without actually use them
	   if the environment doesn't specify this languages. So the following
	   example configuration will result in the order "en, de" in an
	   english and in "de, en" in a german localization. Note that "fr" is
	   downloaded, but not used if APT is not used in a french
	   localization, in such an environment the order would be "fr, de,
	   en".

	       Acquire::Languages { "environment"; "de"; "en"; "none"; "fr"; };

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 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 be blank. This
       will slow down startup but save disk space. It is probably preferred 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
       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.

APT IN DSELECT
       When APT is used as a dselect(1) method several configuration
       directives control the default behaviour. 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 is passed to apt-get(8) as command
	   line options when it is run for the install phase.

       Updateoptions
	   The contents of this variable is 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
       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. 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.

       Pre-Install-Pkgs
	   This is a list of shell commands to run before invoking dpkg. 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 to the commands on standard input the filenames of all
	   .deb files it is going to install, one per line.

	   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 2 is enabled by setting
	   DPkg::Tools::options::cmd::Version to 2.  cmd is a command given to
	   Pre-Install-Pkgs.

       Run-Directory
	   APT chdirs to this directory before invoking dpkg, 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 trigger usage (and related options)
       APT can call dpkg in a way so it can make aggressive use of triggers
       over multiply calls of dpkg. Without further options dpkg will use
       triggers only in between his own run. Activating these options can
       therefore decrease the time needed to perform the install / upgrade.
       Note that it is intended to activate these options per default in the
       future, but as it changes the way APT calling dpkg drastically it needs
       a lot more testing.  These options are therefore currently experimental
       and should not be used in productive environments.  Also it breaks the
       progress reporting so all frontends 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 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";

       DPkg::NoTriggers
	   Add the no triggers flag to all dpkg calls (except the
	   ConfigurePending call). See dpkg(1) if you are interested in what
	   this actually means. In short: dpkg 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 - now apt will add these flag also to the unpack and remove
	   calls.

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

       DPkg::ConfigurePending
	   If this option is set apt will call dpkg --configure --pending to
	   let dpkg handle all required configurations and triggers. This
	   option is activated automatic per default if the previous option is
	   not set to all, but deactivating 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.

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

       PackageManager::UnpackAll
	   As the configuration can be deferred to be done at the end by dpkg
	   it can be tried to order the unpack series only by critical needs,
	   e.g. by Pre-Depends. Default is true and therefore the "old" method
	   of ordering in various steps by everything. While both method were
	   present in earlier APT versions the OrderCritical method was
	   unused, so this method is very experimental and needs further
	   improvements before becoming really useful.

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

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

PERIODIC AND ARCHIVES OPTIONS
       APT::Periodic and APT::Archives groups of options configure behavior of
       apt periodic updates, which is done by /etc/cron.daily/apt script. See
       header 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 CDROM
	   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 package is 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 space 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 version as the
	   installed.  section is the name of the section the package appears
	   in.

       Debug::pkgInitConfig
	   Dump the default configuration to standard error on startup.

       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.

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::*.

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

Linux				16 January 2010			   APT.CONF(5)
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