APT.CONF(5) APT.CONF(5)
NAME
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.
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.
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.
Immediate-Configure
Disable Immediate Configuration; This dangerous option disables some
of APTs 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.
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-Limit
APT uses a fixed size memory mapped cache file to store the
available information. This sets the size of that cache (in
bytes).
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::
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 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 its 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.
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.
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 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.
APT IN DSELECT
When APT is used as a dselect(8) 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(8) 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(8). 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(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.
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.
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 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.
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
SEE ALSO
apt-cache(8), apt-config(8), apt_preferences(5).
BUGS
[1]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.
AUTHORS
Jason Gunthorpe
Author.
APT team
Author.
REFERENCES
1. APT bug page
http://bugs.debian.org/src:apt
Linux 29 February 2004 APT.CONF(5)
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