{
    "mode": "man",
    "parameter": "APT.CONF",
    "section": "",
    "url": "https://www.chedong.com/phpMan.php/man/APT.CONF/json",
    "generated": "2026-10-24T10:58:51Z",
    "sections": {
        "NAME": {
            "content": "apt.conf - Configuration file for APT\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "/etc/apt/apt.conf is the main configuration file shared by all the tools in the APT suite of\ntools, though it is by no means the only place options can be set. The suite also shares a\ncommon command line parser to provide a uniform environment.\n\nWhen an APT tool starts up it will read the configuration files in the following order:\n\n1. the file specified by the APTCONFIG environment variable (if any)\n\n2. all files in Dir::Etc::Parts in alphanumeric ascending order which have either no or\n\"conf\" as filename extension and which only contain alphanumeric, hyphen (-), underscore\n() and period (.) characters. Otherwise APT will print a notice that it has ignored a\nfile, unless that file matches a pattern in the Dir::Ignore-Files-Silently configuration\nlist - in which case it will be silently ignored.\n\n3. the main configuration file specified by Dir::Etc::main\n\n4. all options set in the binary specific configuration subtree are moved into the root of\nthe tree.\n\n5. the command line options are applied to override the configuration directives or to load\neven more configuration files.\n",
            "subsections": []
        },
        "SYNTAX": {
            "content": "The configuration file is organized in a tree with options organized into functional groups.\nOption specification is given with a double colon notation; for instance APT::Get::Assume-Yes\nis an option within the APT tool group, for the Get tool. Options do not inherit from their\nparent groups.\n\nSyntactically the configuration language is modeled after what the ISC tools such as bind and\ndhcp use. Lines starting with // are treated as comments (ignored), as well as all text\nbetween /* and */, just like C/C++ comments. Lines starting with # are also treated as\ncomments. Each line is of the form APT::Get::Assume-Yes \"true\";. The quotation marks and\ntrailing semicolon are required. The value must be on one line, and there is no kind of\nstring concatenation. Values must not include backslashes or extra quotation marks. Option\nnames are made up of alphanumeric characters and the characters \"/-:.+\". A new scope can be\nopened with curly braces, like this:\n\n\nAPT {\nGet {\nAssume-Yes \"true\";\nFix-Broken \"true\";\n};\n};\n\nwith newlines placed to make it more readable. Lists can be created by opening a scope and\nincluding a single string enclosed in quotes followed by a semicolon. Multiple entries can be\nincluded, separated by a semicolon.\n\n\nDPkg::Pre-Install-Pkgs {\"/usr/sbin/dpkg-preconfigure --apt\";};\n\nIn general the sample configuration file /usr/share/doc/apt/examples/configure-index is a\ngood guide for how it should look.\n\nCase is not significant in names of configuration items, so in the previous example you could\nuse dpkg::pre-install-pkgs.\n\nNames for the configuration items are optional if a list is defined as can be seen in the\nDPkg::Pre-Install-Pkgs example above. If you don't specify a name a new entry will simply add\na new option to the list. If you specify a name you can override the option in the same way\nas any other option by reassigning a new value to the option.\n\nTwo special commands are defined: #include (which is deprecated and not supported by\nalternative implementations) and #clear.  #include will include the given file, unless the\nfilename ends in a slash, in which case the whole directory is included.  #clear is used to\nerase a part of the configuration tree. The specified element and all its descendants are\nerased. (Note that these lines also need to end with a semicolon.)\n\nThe #clear command is the only way to delete a list or a complete scope. Reopening a scope\n(or using the syntax described below with an appended ::) will not override previously\nwritten entries. Options can only be overridden by addressing a new value to them - lists and\nscopes can't be overridden, only cleared.\n\nAll of the APT tools take an -o option which allows an arbitrary configuration directive to\nbe specified on the command line. The syntax is a full option name (APT::Get::Assume-Yes for\ninstance) followed by an equals sign then the new value of the option. To append a new\nelement to a list, add a trailing :: to the name of the list. (As you might suspect, the\nscope syntax can't be used on the command line.)\n\nNote that appending items to a list using :: only works for one item per line, and that you\nshould not use it in combination with the scope syntax (which adds :: implicitly). Using both\nsyntaxes together will trigger a bug which some users unfortunately depend on: an option with\nthe unusual name \"::\" which acts like every other option with a name. This introduces many\nproblems; for one thing, users who write multiple lines in this wrong syntax in the hope of\nappending to a list will achieve the opposite, as only the last assignment for this option\n\"::\" will be used. Future versions of APT will raise errors and stop working if they\nencounter this misuse, so please correct such statements now while APT doesn't explicitly\ncomplain about them.\n",
            "subsections": []
        },
        "THE APT GROUP": {
            "content": "This group of options controls general APT behavior as well as holding the options for all of\nthe tools.\n",
            "subsections": [
                {
                    "name": "Architecture",
                    "content": "System Architecture; sets the architecture to use when fetching files and parsing package\nlists. The internal default is the architecture apt was compiled for.\n"
                },
                {
                    "name": "Architectures",
                    "content": "All Architectures the system supports. For instance, CPUs implementing the amd64 (also\ncalled x86-64) instruction set are also able to execute binaries compiled for the i386\n(x86) instruction set. This list is used when fetching files and parsing package lists.\nThe initial default is always the system's native architecture (APT::Architecture), and\nforeign architectures are added to the default list when they are registered via dpkg\n--add-architecture.\n"
                },
                {
                    "name": "Compressor",
                    "content": "This scope defines which compression formats are supported, how compression and\ndecompression can be performed if support for this format isn't built into apt directly\nand a cost-value indicating how costly it is to compress something in this format. As an\nexample the following configuration stanza would allow apt to download and uncompress as\nwell as create and store files with the low-cost .reversed file extension which it will\npass to the command rev without additional commandline parameters for compression and\nuncompression:\n\nAPT::Compressor::rev {\nName \"rev\";\nExtension \".reversed\";\nBinary \"rev\";\nCompressArg {};\nUncompressArg {};\nCost \"10\";\n};\n"
                },
                {
                    "name": "Build-Profiles",
                    "content": "List of all build profiles enabled for build-dependency resolution, without the\n\"profile.\" namespace prefix. By default this list is empty. The DEBBUILDPROFILES as\nused by dpkg-buildpackage(1) overrides the list notation.\n"
                },
                {
                    "name": "Default-Release",
                    "content": "Default release to install packages from if more than one version is available. Contains\nrelease name, codename or release version. Examples: 'stable', 'testing', 'unstable',\n'bookworm', 'trixie', '4.0', '5.0*'. See also aptpreferences(5).\n"
                },
                {
                    "name": "Snapshot",
                    "content": "Snapshot to use for all repositories configured with Snapshot: yes. See also\nsources.list(5), the --snapshot option that sets this value, and Acquire::Snapshots::URI\nbelow.\n"
                },
                {
                    "name": "Ignore-Hold",
                    "content": "Ignore held packages; this global option causes the problem resolver to ignore held\npackages in its decision making.\n"
                },
                {
                    "name": "Clean-Installed",
                    "content": "Defaults to on. When turned on the autoclean feature will remove any packages which can\nno longer be downloaded from the cache. If turned off then packages that are locally\ninstalled are also excluded from cleaning - but note that APT provides no direct means to\nreinstall them.\n"
                },
                {
                    "name": "Immediate-Configure",
                    "content": "Defaults to on, which will cause APT to install essential and important packages as soon\nas possible in an install/upgrade operation, in order to limit the effect of a failing\ndpkg(1) call. If this option is disabled, APT treats an important package in the same way\nas an extra package: between the unpacking of the package A and its configuration there\ncan be many other unpack or configuration calls for other unrelated packages B, C etc. If\nthese cause the dpkg(1) call to fail (e.g. because package B's maintainer scripts\ngenerate an error), this results in a system state in which package A is unpacked but\nunconfigured - so any package depending on A is now no longer guaranteed to work, as its\ndependency on A is no longer satisfied.\n\nThe immediate configuration marker is also applied in the potentially problematic case of\ncircular dependencies, since a dependency with the immediate flag is equivalent to a\nPre-Dependency. In theory this allows APT to recognise a situation in which it is unable\nto perform immediate configuration, abort, and suggest to the user that the option should\nbe temporarily deactivated in order to allow the operation to proceed. Note the use of\nthe word \"theory\" here; in the real world this problem has rarely been encountered, in\nnon-stable distribution versions, and was caused by wrong dependencies of the package in\nquestion or by a system in an already broken state; so you should not blindly disable\nthis option, as the scenario mentioned above is not the only problem it can help to\nprevent in the first place.\n\nBefore a big operation like dist-upgrade is run with this option disabled you should try\nto explicitly install the package APT is unable to configure immediately; but please make\nsure you also report your problem to your distribution and to the APT team with the bug\nlink below, so they can work on improving or correcting the upgrade process.\n"
                },
                {
                    "name": "Force-LoopBreak",
                    "content": "Never enable this option unless you really know what you are doing. It permits APT to\ntemporarily remove an essential package to break a Conflicts/Conflicts or\nConflicts/Pre-Depends loop between two essential packages.  Such a loop should never\nexist and is a grave bug. This option will work if the essential packages are not tar,\ngzip, libc, dpkg, dash or anything that those packages depend on.\n\nCache-Start, Cache-Grow, Cache-Limit\nAPT uses since version 0.7.26 a resizable memory mapped cache file to store the available\ninformation.  Cache-Start acts as a hint of the size the cache will grow to, and is\ntherefore the amount of memory APT will request at startup. The default value is 20971520\nbytes (~20 MB). Note that this amount of space needs to be available for APT; otherwise\nit will likely fail ungracefully, so for memory restricted devices this value should be\nlowered while on systems with a lot of configured sources it should be increased.\nCache-Grow defines in bytes with the default of 1048576 (~1 MB) how much the cache size\nwill be increased in the event the space defined by Cache-Start is not enough. This value\nwill be applied again and again until either the cache is big enough to store all\ninformation or the size of the cache reaches the Cache-Limit. The default of Cache-Limit\nis 0 which stands for no limit. If Cache-Grow is set to 0 the automatic growth of the\ncache is disabled.\n"
                },
                {
                    "name": "Build-Essential",
                    "content": "Defines which packages are considered essential build dependencies.\n"
                },
                {
                    "name": "Get",
                    "content": "The Get subsection controls the apt-get(8) tool; please see its documentation for more\ninformation about the options here.\n"
                },
                {
                    "name": "Cache",
                    "content": "The Cache subsection controls the apt-cache(8) tool; please see its documentation for\nmore information about the options here.\n\nCDROM\nThe CDROM subsection controls the apt-cdrom(8) tool; please see its documentation for\nmore information about the options here.\n"
                },
                {
                    "name": "NeverAutoRemove",
                    "content": "Never autoremove packages that match the regular expression(s).\n"
                },
                {
                    "name": "Protect-Kernels",
                    "content": "This option tells apt autoremove that kernels are protected and defaults to true. In case\nkernels are not protected they are treated as any other package.\n"
                },
                {
                    "name": "VersionedKernelPackages",
                    "content": "Define the regular expression(s) for versioned kernel packages. Based on these\nexpressions a rule set is injected into apt similar to APT::NeverAutoRemove regular\nexpressions.\n"
                },
                {
                    "name": "NeverAutoRemove::KernelCount",
                    "content": "Keep a custom amount of kernels when autoremoving and defaults to 2, meaning two kernels\nare kept. Apt will always keep the running kernel and the latest one. If the latest\nkernel is the same as the running kernel, the second latest kernel is kept. Because of\nthis, any value lower than 2 will be ignored. If you want only the latest kernel, you\nshould set APT::Protect-Kernels to false.\n"
                }
            ]
        },
        "THE ACQUIRE GROUP": {
            "content": "The Acquire group of options controls the download of packages as well as the various\n\"acquire methods\" responsible for the download itself (see also sources.list(5)).\n",
            "subsections": [
                {
                    "name": "Check-Date",
                    "content": "Security related option defaulting to true, enabling time-related checks. Disabling it\nmeans that the machine's time cannot be trusted, and APT will hence disable all\ntime-related checks, such as Check-Valid-Until and verifying that the Date field of a\nrelease file is not in the future.\n"
                },
                {
                    "name": "Max-FutureTime",
                    "content": "Maximum time (in seconds) before its creation (as indicated by the Date header) that the\nRelease file should be considered valid. The default value is 10. Archive specific\nsettings can be made by appending the label of the archive to the option name.\nPreferably, the same can be achieved for specific sources.list(5) entries by using the\nDate-Max-Future option there.\n"
                },
                {
                    "name": "Check-Valid-Until",
                    "content": "Security related option defaulting to true, as giving a Release file's validation an\nexpiration date prevents replay attacks over a long timescale, and can also for example\nhelp users to identify mirrors that are no longer updated - but the feature depends on\nthe correctness of the clock on the user system. Archive maintainers are encouraged to\ncreate Release files with the Valid-Until header, but if they don't or a stricter value\nis desired the Max-ValidTime option below can be used. The Check-Valid-Until option of\nsources.list(5) entries should be preferred to disable the check selectively instead of\nusing this global override.\n"
                },
                {
                    "name": "Max-ValidTime",
                    "content": "Maximum time (in seconds) after its creation (as indicated by the Date header) that the\nRelease file should be considered valid. If the Release file itself includes a\nValid-Until header the earlier date of the two is used as the expiration date. The\ndefault value is 0 which stands for \"valid forever\". Archive specific settings can be\nmade by appending the label of the archive to the option name. Preferably, the same can\nbe achieved for specific sources.list(5) entries by using the Valid-Until-Max option\nthere.\n"
                },
                {
                    "name": "Min-ValidTime",
                    "content": "Minimum time (in seconds) after its creation (as indicated by the Date header) that the\nRelease file should be considered valid. Use this if you need to use a seldom updated\n(local) mirror of a more frequently updated archive with a Valid-Until header instead of\ncompletely disabling the expiration date checking. Archive specific settings can and\nshould be used by appending the label of the archive to the option name. Preferably, the\nsame can be achieved for specific sources.list(5) entries by using the Valid-Until-Min\noption there.\n"
                },
                {
                    "name": "AllowTLS",
                    "content": "Allow use of the internal TLS support in the http method. If set to false, this\ncompletely disables support for TLS in apt's own methods (excluding the curl-based https\nmethod). No TLS-related functions will be called anymore.\n"
                },
                {
                    "name": "PDiffs",
                    "content": "Try to download deltas called PDiffs for indexes (like Packages files) instead of\ndownloading whole ones. True by default. Preferably, this can be set for specific\nsources.list(5) entries or index files by using the PDiffs option there.\n\nTwo sub-options to limit the use of PDiffs are also available: FileLimit can be used to\nspecify a maximum number of PDiff files should be downloaded to update a file.  SizeLimit\non the other hand is the maximum percentage of the size of all patches compared to the\nsize of the targeted file. If one of these limits is exceeded the complete file is\ndownloaded instead of the patches.\n"
                },
                {
                    "name": "By-Hash",
                    "content": "Try to download indexes via an URI constructed from a hashsum of the expected file rather\nthan downloaded via a well-known stable filename. True by default, but automatically\ndisabled if the source indicates no support for it. Usage can be forced with the special\nvalue \"force\". Preferably, this can be set for specific sources.list(5) entries or index\nfiles by using the By-Hash option there.\n"
                },
                {
                    "name": "Queue-Mode",
                    "content": "Queuing mode; Queue-Mode can be one of host or access which determines how APT\nparallelizes outgoing connections.  host means that one connection per target host will\nbe opened, access means that one connection per URI type will be opened.\n"
                },
                {
                    "name": "Retries",
                    "content": "Number of retries to perform. If this is non-zero APT will retry failed files the given\nnumber of times.\n"
                },
                {
                    "name": "Source-Symlinks",
                    "content": "Use symlinks for source archives. If set to true then source archives will be symlinked\nwhen possible instead of copying. True is the default.\n"
                },
                {
                    "name": "http https",
                    "content": "The options in these scopes configure APT's acquire transports for the protocols HTTP and\nHTTPS and are documented in the apt-transport-http(1) and apt-transport-https(1) manpages\nrespectively.\n"
                },
                {
                    "name": "ftp",
                    "content": "ftp::Proxy sets the default proxy to use for FTP URIs. It is in the standard form of\nftp://[[user][:pass]@]host[:port]/. Per host proxies can also be specified by using the\nform ftp::Proxy::<host> with the special keyword DIRECT meaning to use no proxies. If no\none of the above settings is specified, ftpproxy environment variable will be used. To\nuse an FTP proxy you will have to set the ftp::ProxyLogin script in the configuration\nfile. This entry specifies the commands to send to tell the proxy server what to connect\nto. Please see /usr/share/doc/apt/examples/configure-index for an example of how to do\nthis. The substitution variables representing the corresponding URI component are\n$(PROXYUSER), $(PROXYPASS), $(SITEUSER), $(SITEPASS), $(SITE) and $(SITEPORT).\n\nThe option timeout sets the timeout timer used by the method; this value applies to the\nconnection as well as the data timeout.\n\nSeveral settings are provided to control passive mode. Generally it is safe to leave\npassive mode on; it works in nearly every environment. However, some situations require\nthat passive mode be disabled and port mode FTP used instead. This can be done globally\nor for connections that go through a proxy or for a specific host (see the sample config\nfile for examples).\n\nIt is possible to proxy FTP over HTTP by setting the ftpproxy environment variable to an\nHTTP URL - see the discussion of the http method above for syntax. You cannot set this in\nthe configuration file and it is not recommended to use FTP over HTTP due to its low\nefficiency.\n\nThe setting ForceExtended controls the use of RFC2428 EPSV and EPRT commands. The default\nis false, which means these commands are only used if the control connection is IPv6.\nSetting this to true forces their use even on IPv4 connections. Note that most FTP\nservers do not support RFC2428.\n"
                },
                {
                    "name": "cdrom",
                    "content": "For URIs using the cdrom method, the only configurable option is the mount point,\ncdrom::Mount, which must be the mount point for the CD-ROM (or DVD, or whatever) drive as\nspecified in /etc/fstab. It is possible to provide alternate mount and unmount commands\nif your mount point cannot be listed in the fstab. The syntax is to put\n\n/cdrom/::Mount \"foo\";\n\nwithin the cdrom block. It is important to have the trailing slash. Unmount commands can\nbe specified using UMount.\n"
                },
                {
                    "name": "gpgv",
                    "content": "For GPGV URIs the only configurable option is gpgv::Options, which passes additional\nparameters to gpgv.\n"
                },
                {
                    "name": "CompressionTypes",
                    "content": "List of compression types which are understood by the acquire methods. Files like\nPackages can be available in various compression formats. By default the acquire methods\ncan decompress and recompress many common formats like xz and gzip; with this scope the\nsupported formats can be queried, modified as well as support for more formats added (see\nalso APT::Compressor). The syntax for this is:\n\nAcquire::CompressionTypes::FileExtension \"Methodname\";\n\nAlso, the Order subgroup can be used to define in which order the acquire system will try\nto download the compressed files. The acquire system will try the first and proceed with\nthe next compression type in this list on error, so to prefer one over the other type\nsimply add the preferred type first - types not already added will be implicitly appended\nto the end of the list, so e.g.\n\nAcquire::CompressionTypes::Order:: \"gz\";\n\ncan be used to prefer gzip compressed files over all other compression formats. If xz\nshould be preferred over gzip and bzip2 the configure setting should look like this:\n\nAcquire::CompressionTypes::Order { \"xz\"; \"gz\"; };\n\nIt is not needed to add bz2 to the list explicitly as it will be added automatically.\n\nNote that the Dir::Bin::Methodname will be checked at run time. If this option has been\nset and support for this format isn't directly built into apt, the method will only be\nused if this file exists; e.g. for the bzip2 method (the inbuilt) setting is:\n\nDir::Bin::bzip2 \"/bin/bzip2\";\n\nNote also that list entries specified on the command line will be added at the end of the\nlist specified in the configuration files, but before the default entries. To prefer a\ntype in this case over the ones specified in the configuration files you can set the\noption direct - not in list style. This will not override the defined list; it will only\nprefix the list with this type.\n\nThe special type uncompressed can be used to give uncompressed files a preference, but\nnote that most archives don't provide uncompressed files so this is mostly only usable\nfor local mirrors.\n"
                },
                {
                    "name": "GzipIndexes",
                    "content": "When downloading gzip compressed indexes (Packages, Sources, or Translations), keep them\ngzip compressed locally instead of unpacking them. This saves quite a lot of disk space\nat the expense of more CPU requirements when building the local package caches. False by\ndefault.\n"
                },
                {
                    "name": "Languages",
                    "content": "The Languages subsection controls which Translation files are downloaded and in which\norder APT tries to display the description-translations. APT will try to display the\nfirst available description in the language which is listed first. Languages can be\ndefined with their short or long language codes. Note that not all archives provide\nTranslation files for every language - the long language codes are especially rare.\n\nThe default list includes \"environment\" and \"en\". \"environment\" has a special meaning\nhere: it will be replaced at runtime with the language codes extracted from the\nLCMESSAGES environment variable. It will also ensure that these codes are not included\ntwice in the list. If LCMESSAGES is set to \"C\" only the Translation-en file (if\navailable) will be used. To force APT to use no Translation file use the setting\nAcquire::Languages=none. \"none\" is another special meaning code which will stop the\nsearch for a suitable Translation file. This tells APT to download these translations\ntoo, without actually using them unless the environment specifies the languages. So the\nfollowing example configuration will result in the order \"en, de\" in an English locale or\n\"de, en\" in a German one. Note that \"fr\" is downloaded, but not used unless APT is used\nin a French locale (where the order would be \"fr, de, en\").\n\nAcquire::Languages { \"environment\"; \"de\"; \"en\"; \"none\"; \"fr\"; };\n\nNote: To prevent problems resulting from APT being executed in different environments\n(e.g. by different users or by other programs) all Translation files which are found in\n/var/lib/apt/lists/ will be added to the end of the list (after an implicit \"none\").\n"
                },
                {
                    "name": "ForceIPv4",
                    "content": "When downloading, force to use only the IPv4 protocol.\n"
                },
                {
                    "name": "ForceIPv6",
                    "content": "When downloading, force to use only the IPv6 protocol.\n"
                },
                {
                    "name": "MaxReleaseFileSize",
                    "content": "The maximum file size of Release/Release.gpg/InRelease files. The default is 10MB.\n"
                },
                {
                    "name": "EnableSrvRecords",
                    "content": "This option controls if apt will use the DNS SRV server record as specified in RFC 2782\nto select an alternative server to connect to. The default is \"true\".\n"
                },
                {
                    "name": "AllowInsecureRepositories",
                    "content": "Allow update operations to load data files from repositories without sufficient security\ninformation. The default value is \"false\". Concept, implications as well as alternatives\nare detailed in apt-secure(8).\n"
                },
                {
                    "name": "AllowWeakRepositories",
                    "content": "Allow update operations to load data files from repositories which provide security\ninformation, but these are deemed no longer cryptographically strong enough. The default\nvalue is \"false\". Concept, implications as well as alternatives are detailed in apt-\nsecure(8).\n"
                },
                {
                    "name": "AllowDowngradeToInsecureRepositories",
                    "content": "Allow that a repository that was previously gpg signed to become unsigned during an\nupdate operation. When there is no valid signature for a previously trusted repository\napt will refuse the update. This option can be used to override this protection. You\nalmost certainly never want to enable this. The default is false. Concept, implications\nas well as alternatives are detailed in apt-secure(8).\n\nChangelogs::URI scope\nAcquiring changelogs can only be done if an URI is known from where to get them.\nPreferable the Release file indicates this in a 'Changelogs' field. If this isn't\navailable the Label/Origin field of the Release file is used to check if a\nAcquire::Changelogs::URI::Label::LABEL or Acquire::Changelogs::URI::Origin::ORIGIN option\nexists and if so this value is taken. The value in the Release file can be overridden\nwith Acquire::Changelogs::URI::Override::Label::LABEL or\nAcquire::Changelogs::URI::Override::Origin::ORIGIN. The value should be a normal URI to a\ntext file, except that package specific data is replaced with the placeholder\n@CHANGEPATH@. The value for it is: 1. if the package is from a component (e.g.  main)\nthis is the first part otherwise it is omitted, 2. the first letter of source package\nname, except if the source package name starts with 'lib' in which case it will be the\nfirst four letters. 3. The complete source package name. 4. the complete name again and\n5. the source version. The first (if present), second, third and fourth part are\nseparated by a slash ('/') and between the fourth and fifth part is an underscore ('').\nThe special value 'no' is available for this option indicating that this source can't be\nused to acquire changelog files from. Another source will be tried if available in this\ncase.\n\nSnapshots::URI scope\nLike changelogs, snapshots can only be acquired if an URI is known from where to get\nthem. Preferable the Release file indicates this in a 'Snapshots' field. If this isn't\navailable the Label/Origin field of the Release file is used to check if a\nAcquire::Snapshots::URI::Label::LABEL or Acquire::Snapshots::URI::Origin::ORIGIN option\nexists and if so this value is taken. The value in the Release file can be overridden\nwith Acquire::Snapshots::URI::Override::Label::LABEL or\nAcquire::Snapshots::URI::Override::Origin::ORIGIN. The value should be a normal URI to a\ndirectory, except that the snapshot ID replaced with the placeholder @SNAPSHOTID. The\nspecial value 'no' is available for this option indicating that this source cannot be\nused to acquire snapshots from. Another source will be tried if available in this case.\n"
                }
            ]
        },
        "BINARY SPECIFIC CONFIGURATION": {
            "content": "Especially with the introduction of the apt binary it can be useful to set certain options\nonly for a specific binary as even options which look like they would effect only a certain\nbinary like APT::Get::Show-Versions effect apt-get as well as apt.\n\nSetting an option for a specific binary only can be achieved by setting the option inside the\nBinary::specific-binary scope. Setting the option APT::Get::Show-Versions for the apt only\ncan e.g. by done by setting Binary::apt::APT::Get::Show-Versions instead.\n\nNote that as seen in the DESCRIPTION section further above you can't set binary-specific\noptions on the commandline itself nor in configuration files loaded via the commandline.\n",
            "subsections": []
        },
        "DIRECTORIES": {
            "content": "The Dir::State section has directories that pertain to local state information.  lists is the\ndirectory to place downloaded package lists in and status is the name of the dpkg(1) status\nfile.  preferences is the name of the APT preferences file.  Dir::State contains the default\ndirectory to prefix on all sub-items if they do not start with / or ./.\n\nDir::Cache contains locations pertaining to local cache information, such as the two package\ncaches srcpkgcache and pkgcache as well as the location to place downloaded archives,\nDir::Cache::archives. Generation of caches can be turned off by setting pkgcache or\nsrcpkgcache to \"\". This will slow down startup but save disk space. It is probably preferable\nto turn off the pkgcache rather than the srcpkgcache. Like Dir::State the default directory\nis contained in Dir::Cache\n\nDir::Etc contains the location of configuration files, sourcelist gives the location of the\nsourcelist and main is the default configuration file (setting has no effect, unless it is\ndone from the config file specified by APTCONFIG).\n\nThe Dir::Parts setting reads in all the config fragments in lexical order from the directory\nspecified. After this is done then the main config file is loaded.\n\nBinary programs are pointed to by Dir::Bin.  Dir::Bin::Methods specifies the location of the\nmethod handlers and gzip, bzip2, lzma, dpkg, apt-get dpkg-source dpkg-buildpackage and\napt-cache specify the location of the respective programs.\n\nThe configuration item RootDir has a special meaning. If set, all paths will be relative to\nRootDir, even paths that are specified absolutely. So, for instance, if RootDir is set to\n/tmp/staging and Dir::State::status is set to /var/lib/dpkg/status, then the status file will\nbe looked up in /tmp/staging/var/lib/dpkg/status. If you want to prefix only relative paths,\nset Dir instead.\n\nThe Ignore-Files-Silently list can be used to specify which files APT should silently ignore\nwhile parsing the files in the fragment directories. Per default a file which ends with\n.disabled, ~, .bak or .dpkg-[a-z]+ is silently ignored. As seen in the last default value\nthese patterns can use regular expression syntax.\n",
            "subsections": []
        },
        "APT IN DSELECT": {
            "content": "When APT is used as a dselect(1) method several configuration directives control the default\nbehavior. These are in the DSelect section.\n",
            "subsections": [
                {
                    "name": "Clean",
                    "content": "Cache Clean mode; this value may be one of always, prompt, auto, pre-auto and never.\nalways and prompt will remove all packages from the cache after upgrading, prompt (the\ndefault) does so conditionally.  auto removes only those packages which are no longer\ndownloadable (replaced with a new version for instance).  pre-auto performs this action\nbefore downloading new packages.\n"
                },
                {
                    "name": "options",
                    "content": "The contents of this variable are passed to apt-get(8) as command line options when it is\nrun for the install phase.\n"
                },
                {
                    "name": "Updateoptions",
                    "content": "The contents of this variable are passed to apt-get(8) as command line options when it is\nrun for the update phase.\n"
                },
                {
                    "name": "PromptAfterUpdate",
                    "content": "If true the [U]pdate operation in dselect(1) will always prompt to continue. The default\nis to prompt only on error.\n\nHOW APT CALLS DPKG(1)\nSeveral configuration directives control how APT invokes dpkg(1). These are in the DPkg\nsection.\n"
                },
                {
                    "name": "options",
                    "content": "This is a list of options to pass to dpkg(1). The options must be specified using the\nlist notation and each list item is passed as a single argument to dpkg(1).\n"
                },
                {
                    "name": "Path",
                    "content": "This is a string that defines the PATH environment variable used when running dpkg. It\nmay be set to any valid value of that environment variable; or the empty string, in which\ncase the variable is not changed.\n\nPre-Invoke, Post-Invoke\nThis is a list of shell commands to run before/after invoking dpkg(1). Like options this\nmust be specified in list notation. The commands are invoked in order using /bin/sh;\nshould any fail APT will abort.\n"
                },
                {
                    "name": "Pre-Install-Pkgs",
                    "content": "This is a list of shell commands to run before invoking dpkg(1). Like options this must\nbe specified in list notation. The commands are invoked in order using /bin/sh; should\nany fail APT will abort. APT will pass the filenames of all .deb files it is going to\ninstall to the commands, one per line on the requested file descriptor, defaulting to\nstandard input.\n\nVersion 2 of this protocol sends more information through the requested file descriptor:\na line with the text VERSION 2, the APT configuration space, and a list of package\nactions with filename and version information.\n\nEach configuration directive line has the form key=value. Special characters (equal\nsigns, newlines, nonprintable characters, quotation marks, and percent signs in key and\nnewlines, nonprintable characters, and percent signs in value) are %-encoded. Lists are\nrepresented by multiple key::=value lines with the same key. The configuration section\nends with a blank line.\n\nPackage action lines consist of five fields in Version 2: package name (without\narchitecture qualification even if foreign), old version, direction of version change (<\nfor upgrades, > for downgrades, = for no change), new version, action. The version fields\nare \"-\" for no version at all (for example when installing a package for the first time;\nno version is treated as earlier than any real version, so that is an upgrade, indicated\nas - < 1.23.4). The action field is \"CONFIGURE\" if the package is being configured,\n\"REMOVE\" if it is being removed, or the filename of a .deb file if it is being\nunpacked.\n\nIn Version 3 after each version field follows the architecture of this version, which is\n\"-\" if there is no version, and a field showing the MultiArch type \"same\", \"foreign\",\n\"allowed\" or \"none\". Note that \"none\" is an incorrect typename which is just kept to\nremain compatible, it should be read as \"no\" and users are encouraged to support both.\n\nThe version of the protocol to be used for the command cmd can be chosen by setting\nDPkg::Tools::options::cmd::Version accordingly, the default being version 1. If APT isn't\nsupporting the requested version it will send the information in the highest version it\nhas support for instead.\n\nThe file descriptor to be used to send the information can be requested with\nDPkg::Tools::options::cmd::InfoFD which defaults to 0 for standard input and is available\nsince version 0.9.11. Support for the option can be detected by looking for the\nenvironment variable APTHOOKINFOFD which contains the number of the used file\ndescriptor as a confirmation.\n"
                },
                {
                    "name": "Run-Directory",
                    "content": "APT chdirs to this directory before invoking dpkg(1), the default is /.\n"
                },
                {
                    "name": "Build-options",
                    "content": "These options are passed to dpkg-buildpackage(1) when compiling packages; the default is\nto disable signing and produce all binaries.\n"
                },
                {
                    "name": "DPkg::ConfigurePending",
                    "content": "If this option is set APT will call dpkg --configure --pending to let dpkg(1) handle all\nrequired configurations and triggers. This option is activated by default, but\ndeactivating it could be useful if you want to run APT multiple times in a row - e.g. in\nan installer. In this scenario you could deactivate this option in all but the last run.\n"
                }
            ]
        },
        "PERIODIC AND ARCHIVES OPTIONS": {
            "content": "APT::Periodic and APT::Archives groups of options configure behavior of apt periodic updates,\nwhich is done by the /usr/lib/apt/apt.systemd.daily script. See the top of this script for\nthe brief documentation of these options.\n",
            "subsections": []
        },
        "DEBUG OPTIONS": {
            "content": "Enabling options in the Debug:: section will cause debugging information to be sent to the\nstandard error stream of the program utilizing the apt libraries, or enable special program\nmodes that are primarily useful for debugging the behavior of apt. Most of these options are\nnot interesting to a normal user, but a few may be:\n\n•   Debug::pkgProblemResolver enables output about the decisions made by dist-upgrade,\nupgrade, install, remove, purge.\n\n•   Debug::NoLocking disables all file locking. This can be used to run some operations (for\ninstance, apt-get -s install) as a non-root user.\n\n•   Debug::pkgDPkgPM prints out the actual command line each time that apt invokes dpkg(1).\n\n•   Debug::IdentCdrom disables the inclusion of statfs data in CD-ROM IDs.\n\nA full list of debugging options to apt follows.\n",
            "subsections": [
                {
                    "name": "Debug::Acquire::cdrom",
                    "content": "Print information related to accessing cdrom:// sources.\n"
                },
                {
                    "name": "Debug::Acquire::ftp",
                    "content": "Print information related to downloading packages using FTP.\n"
                },
                {
                    "name": "Debug::Acquire::http",
                    "content": "Print information related to downloading packages using HTTP.\n"
                },
                {
                    "name": "Debug::Acquire::https",
                    "content": "Print information related to downloading packages using HTTPS.\n"
                },
                {
                    "name": "Debug::Acquire::gpgv",
                    "content": "Print information related to verifying cryptographic signatures using gpg.\n"
                },
                {
                    "name": "Debug::aptcdrom",
                    "content": "Output information about the process of accessing collections of packages stored on\nCD-ROMs.\n"
                },
                {
                    "name": "Debug::Hashes",
                    "content": "Output each cryptographic hash that is generated by the apt libraries.\n"
                },
                {
                    "name": "Debug::IdentCDROM",
                    "content": "Do not include information from statfs, namely the number of used and free blocks on the\nCD-ROM filesystem, when generating an ID for a CD-ROM.\n"
                },
                {
                    "name": "Debug::NoLocking",
                    "content": "Disable all file locking. For instance, this will allow two instances of “apt-get update”\nto run at the same time.\n"
                },
                {
                    "name": "Debug::pkgAcquire",
                    "content": "Log when items are added to or removed from the global download queue.\n"
                },
                {
                    "name": "Debug::pkgAcquire::Auth",
                    "content": "Output status messages and errors related to verifying checksums and cryptographic\nsignatures of downloaded files.\n"
                },
                {
                    "name": "Debug::pkgAcquire::Diffs",
                    "content": "Output information about downloading and applying package index list diffs, and errors\nrelating to package index list diffs.\n"
                },
                {
                    "name": "Debug::pkgAcquire::RRed",
                    "content": "Output information related to patching apt package lists when downloading index diffs\ninstead of full indices.\n"
                },
                {
                    "name": "Debug::pkgAcquire::Worker",
                    "content": "Log all interactions with the sub-processes that actually perform downloads.\n"
                },
                {
                    "name": "Debug::pkgAutoRemove",
                    "content": "Log events related to the automatically-installed status of packages and to the removal\nof unused packages.\n"
                },
                {
                    "name": "Debug::pkgDepCache::AutoInstall",
                    "content": "Generate debug messages describing which packages are being automatically installed to\nresolve dependencies. This corresponds to the initial auto-install pass performed in,\ne.g., apt-get install, and not to the full apt dependency resolver; see\nDebug::pkgProblemResolver for that.\n"
                },
                {
                    "name": "Debug::pkgDepCache::Marker",
                    "content": "Generate debug messages describing which packages are marked as keep/install/remove while\nthe ProblemResolver does his work. Each addition or deletion may trigger additional\nactions; they are shown indented two additional spaces under the original entry. The\nformat for each line is MarkKeep, MarkDelete or MarkInstall followed by package-name\n<a.b.c -> d.e.f | x.y.z> (section) where a.b.c is the current version of the package,\nd.e.f is the version considered for installation and x.y.z is a newer version, but not\nconsidered for installation (because of a low pin score). The later two can be omitted if\nthere is none or if it is the same as the installed version.  section is the name of the\nsection the package appears in.\n"
                },
                {
                    "name": "Debug::pkgDPkgPM",
                    "content": "When invoking dpkg(1), output the precise command line with which it is being invoked,\nwith arguments separated by a single space character.\n"
                },
                {
                    "name": "Debug::pkgDPkgProgressReporting",
                    "content": "Output all the data received from dpkg(1) on the status file descriptor and any errors\nencountered while parsing it.\n"
                },
                {
                    "name": "Debug::pkgOrderList",
                    "content": "Generate a trace of the algorithm that decides the order in which apt should pass\npackages to dpkg(1).\n"
                },
                {
                    "name": "Debug::pkgPackageManager",
                    "content": "Output status messages tracing the steps performed when invoking dpkg(1).\n"
                },
                {
                    "name": "Debug::pkgPolicy",
                    "content": "Output the priority of each package list on startup.\n"
                },
                {
                    "name": "Debug::pkgProblemResolver",
                    "content": "Trace the execution of the dependency resolver (this applies only to what happens when a\ncomplex dependency problem is encountered).\n"
                },
                {
                    "name": "Debug::pkgProblemResolver::ShowScores",
                    "content": "Display a list of all installed packages with their calculated score used by the\npkgProblemResolver. The description of the package is the same as described in\nDebug::pkgDepCache::Marker\n"
                },
                {
                    "name": "Debug::sourceList",
                    "content": "Print information about the vendors read from /etc/apt/vendors.list.\n"
                },
                {
                    "name": "Debug::RunScripts",
                    "content": "Display the external commands that are called by apt hooks. This includes e.g. the config\noptions DPkg::{Pre,Post}-Invoke or APT::Update::{Pre,Post}-Invoke.\n"
                }
            ]
        },
        "EXAMPLES": {
            "content": "/usr/share/doc/apt/examples/configure-index is a configuration file showing example values\nfor all possible options.\n",
            "subsections": []
        },
        "FILES": {
            "content": "/etc/apt/apt.conf\nAPT configuration file. Configuration Item: Dir::Etc::Main.\n\n/etc/apt/apt.conf.d/\nAPT configuration file fragments. Configuration Item: Dir::Etc::Parts.\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "apt-cache(8), apt-config(8), aptpreferences(5).\n",
            "subsections": []
        },
        "BUGS": {
            "content": "APT bug page[1]. If you wish to report a bug in APT, please see\n/usr/share/doc/debian/bug-reporting.txt or the reportbug(1) command.\n",
            "subsections": []
        },
        "AUTHORS": {
            "content": "",
            "subsections": [
                {
                    "name": "Jason Gunthorpe",
                    "content": ""
                },
                {
                    "name": "APT team",
                    "content": "Daniel Burrows <dburrows@debian.org>\nInitial documentation of Debug::*.\n"
                }
            ]
        },
        "NOTES": {
            "content": "1. APT bug page\nhttps://bugs.debian.org/src:apt\n\nAPT 2.8.3                                 21 February 2024                               APT.CONF(5)",
            "subsections": []
        }
    },
    "summary": "apt.conf - Configuration file for APT",
    "flags": [],
    "examples": [
        "/usr/share/doc/apt/examples/configure-index is a configuration file showing example values",
        "for all possible options."
    ],
    "see_also": [
        {
            "name": "apt-cache",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/apt-cache/8/json"
        },
        {
            "name": "apt-config",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/apt-config/8/json"
        },
        {
            "name": "aptpreferences",
            "section": "5",
            "url": "https://www.chedong.com/phpMan.php/man/aptpreferences/5/json"
        }
    ],
    "tldr": {
        "source": "not_found",
        "examples": []
    }
}