Provided by: apt_0.6.43.3ubuntu2_i386 bug


       apt.conf - Configuration file for APT


       apt.conf is the main configuration file for the APT suite of tools, all
       tools make use of the configuration file  and  a  common  command  line
       parser  to provide a uniform environment. When an APT tool starts up it
       will read the configuration specified  by  the  APT_CONFIG  environment
       variable  (if any) and then read the files in Dir::Etc::Parts then read
       the main configuration file specified by  Dir::Etc::main  then  finally
       apply   the   command   line  options  to  override  the  configuration
       directives, possibly loading even more config 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.

       Syntacticly the configuration language is modeled after  what  the  ISC
       tools  such as bind and dhcp use. Lines starting with // are treated as
       comments (ignored). Each  line  is  of  the  form  APT::Get::Assume-Yes
       "true"; The trailing semicolon is required and the quotes are optional.
       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 word enclosed in quotes followed
       by a semicolon. Multiple entries can be included, each separated  by  a

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

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

       Two specials are allowed, #include 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 list of names.

       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.


       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.

              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.

              Disable Immediate Configuration; This dangerous option  disables
              some  of  APT’s  ordering  code  to  cause it to make fewer dpkg
              calls. Doing so may be necessary on some extremely  slow  single
              user systems but is very dangerous and may cause package install
              scripts to fail or worse. Use at your own risk.

              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.

              APT uses a fixed size memory mapped  cache  file  to  store  the
              ’available’  information.  This  sets the size of that cache (in

              Defines  which  package(s)  are   considered   essential   build

       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 of options controls the download of packages and  the
       URI handlers.

              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   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.  The  http_proxy  environment  variable  will
              override all settings.

              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

              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

       ftp    FTP URIs; ftp::Proxy is the default proxy server to use.  It  is
              in  the  standard form of ftp://[[user][:pass]@]host[:port]/ and
              is overridden by the ftp_proxy environment variable.  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  subsitution  variables  available  are
              $(PROXY_USER)    $(PROXY_PASS)     $(SITE_USER)     $(SITE_PASS)
              $(SITE)  and $(SITE_PORT) Each is taken from it’s respective URI

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

              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 defaut 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.


       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 prefered  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,   dpkg,   apt-get
       dpkg-source   dpkg-buildpackage  and  apt-cache specify the location of
       the respective programs.


       When  APT  is  used  as  a  dselect(8)  method  several   configuration
       directives  control  the  default  behaviour.  These are in the DSelect

       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.

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

              The contents of this variable is 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(8) will always prompt
              to continue. The default is to prompt only on error.


       Several configuration directives control how APT invokes dpkg(8). These
       are in the DPkg section.

              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(8).

       Pre-Invoke, Post-Invoke
              This  is  a  list of shell commands to run before/after invoking
              dpkg(8). 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.
              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

              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.

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

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


       Most of the options in the debug section are  not  interesting  to  the
       normal user, however Debug::pkgProblemResolver shows interesting output
       about the decisions dist-upgrade makes. Debug::NoLocking disables  file
       locking  so APT can do some operations as non-root and Debug::pkgDPkgPM
       will  print  out  the  command   line   for   each   dpkg   invokation.
       Debug::IdentCdrom  will  disable  the inclusion of statfs data in CDROM
       IDs. Debug::Acquire::gpgv Debugging of the gpgv method.


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




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


       APT  bug  page: 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.