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. 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 seperated by a
semicolon.
DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
In general the sample configuration file in /usr/share/doc/apt//exam-
ples/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 arbitary 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 behavoir as well as holding
the options for all of the tools.
Architecture [Toc] [Back]
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 [Toc] [Back]
Ignore Held packages; This global option causes the problem
resolver to ignore held packages in its decision making.
Clean-Installed [Toc] [Back]
Defaults to on. When turned on the autoclean feature will remove
any pacakge 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 [Toc] [Back]
Disable Immedate 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.
Force-LoopBreak [Toc] [Back]
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 [Toc] [Back]
APT uses a fixed size memory mapped cache file to store the
'available' information. This sets the size of that cache.
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.
Queue-Mode [Toc] [Back]
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 [Toc] [Back]
Number of retries to perform. If this is non-zero APT will retry
failed files the given number of times.
Source-Symlinks [Toc] [Back]
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 complient
proxy caches. No-Cache tells the proxy to not used 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 overriden 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.
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. methods specifies the location
of the method handlers and gzip, dpkg, apt-get, dpkg-source, dpkgbuildpackage
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 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 [Toc] [Back]
The contents of this variable is passed to apt-get(8) as command
line options when it is run for the install phase.
UpdateOptions [Toc] [Back]
The contents of this variable is passed to apt-get(8) as command
line options when it is run for the update phase.
PromptAfterUpdate [Toc] [Back]
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.
Options [Toc] [Back]
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 [Toc] [Back]
Post-Invoke [Toc] [Back]
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 [Toc] [Back]
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 [Toc] [Back]
APT chdirs to this directory before invoking dpkg, the default
is /.
Build-Options [Toc] [Back]
These options are passed to dpkg-buildpackage(1) when compiling
packages, the default is to disable signing and produce all
binaries.
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.
/usr/share/doc/apt/examples/configure-index.gz contains a sample configuration
file showing the default values for all possible options.
/etc/apt/apt.conf
apt-cache(8), apt-config(8), apt_preferences(5).
See the APT bug page <URL:http://bugs.debian.org/apt>. If you wish to
report a bug in APT, please see /usr/share/doc/debian/bug-reporting.txt
or the bug(1) command.
APT was written by the APT team <[email protected]>.
12 March 2001 APT.CONF(5)
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