apt.conf man page

apt.conf — Configuration file for APT

Description

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 semicolon:

RPM::Allow-Duplicated {"kernel"; "kernel-smp";};

In general the sample configuration file in /usr/share/doc/apt/examples/apt.conf and /usr/share/doc/apt/examples/configure-index.gz are good guides 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.

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.
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.
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 gzip, libc, rpm, bash or anything that those packages depend on.
Cache-Limit
APT uses a fixed size memory mapped cache file to store the 'available' information. This sets the size of that cache.
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.

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. 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; 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 .rpm 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.

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 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 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.

Directories

The Dir::State section has directories that pertain to local state information. lists is the directory to place downloaded package lists in. 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 the "APT_CONFIG" environment variable).

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 while gzip, rpm, apt-get, rpmbuild and apt-cache specify the location of their respective programs.

How Apt Calls Rpm

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

Options
This is a list of options to pass to rpm(8) for all install, upgrade and remove operations. The options must be specified using the list notation and each list item is passed as a single argument.
Install-Options
This is a list of options to pass to rpm(8) during install and upgrade operations. The options must be specified using the list notation and each list item is passed as a single argument.
Erase-Options
This is a list of options to pass to rpm(8) during remove operations. The options must be specified using the list notation and each list item is passed as a single argument.
Pre-Invoke, Post-Invoke
This is a list of shell commands to run before/after invoking rpm(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.
Pre-Install-Pkgs

This is a list of shell commands to run before invoking rpm(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. APT will pass to the commands on standard input the filenames of all .rpm 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 rpm(8), the default is /.
Build-Options
These options are passed to rpmbuild(8) when compiling packages.

Debug Options

Most of the options in the debug section are not interesting to the normal user, however Debug::pkgProblemResolver shows interesting output about the decisions apt-get dist-upgrade makes. Debug::NoLocking disables file locking so APT can do some operations as non-root and Debug::pkgRPMPM will print out the command-line for each rpm(8) invocation. Debug::IdentCdrom will disable the inclusion of statfs data in CDROM IDs.

Examples

/usr/share/doc/apt/examples/configure-index.gz contains a sample configuration file showing the default values for all possible options.

Files

/etc/apt/apt.conf

See Also

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

Bugs

Reporting bugs in APT-RPM is best done in the APT-RPM mailinglist at http://apt-rpm.org/mailinglist.shtml.

Author

Maintainer and contributor information can be found in the credits page http://apt-rpm.org/about.shtml of APT-RPM.

Referenced By

apt(8), apt-cache(8), apt-cdrom(8), apt-config(8), apt-get(8), apt_preferences(5), sources.list(5), vendors.list(5).

14 Jun 2006 APT-RPM apt.conf