apt-pkg/packagemanager.cc: tweak MaxLoopCount to 500 and improve the error message

[apt.git] / doc / sources.list.5.xml

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<refentry>

 <refentryinfo>
   &apt-author.jgunthorpe;
   &apt-author.team;
   &apt-email;
   &apt-product;
   <!-- The last update date -->
   <date>29 February 2004</date>
 </refentryinfo>
 
 <refmeta>
   <refentrytitle>sources.list</refentrytitle>
   <manvolnum>5</manvolnum>
   <refmiscinfo class="manual">APT</refmiscinfo>
 </refmeta>
 
 <!-- Man page title -->
 <refnamediv>
    <refname>sources.list</refname>
    <refpurpose>Package resource list for APT</refpurpose>
 </refnamediv>
 
 <refsect1><title>Description</title>
   <para>The package resource list is used to locate archives of the package
   distribution system in use on the system. At this time, this manual page
   documents only the packaging system used by the Debian GNU/Linux system.
   This control file is <filename>/etc/apt/sources.list</filename>.</para>

   <para>The source list is designed to support any number of active sources and a
   variety of source media. The file lists one source per line, with the
   most preferred source listed first. The format of each line is:
   <literal>type uri args</literal> The first item, <literal>type</literal>
   determines the format for <literal>args</literal>. <literal>uri</literal> is
   a Universal Resource Identifier 
   (URI), which is a superset of the more specific and well-known Universal
   Resource Locator, or URL. The rest of the line can be marked as a comment 
   by using a #.</para>
 </refsect1>
 
 <refsect1><title>sources.list.d</title>
   <para>The <filename>/etc/apt/sources.list.d</filename> directory provides
   a way to add sources.list entries in separate files.
   The format is the same as for the regular <filename>sources.list</filename> file.
   File names need to end with
   <filename>.list</filename> and may only contain letters (a-z and A-Z),
   digits (0-9), underscore (_), hyphen (-) and period (.) characters.
   Otherwise APT will print a notice that it has ignored a file if the file
   doesn't match a pattern in the <literal>Dir::Ignore-Files-Silently</literal>
   configuration list - in this case it will be silently ignored.</para>
 </refsect1>

 <refsect1><title>The deb and deb-src types</title>
   <para>The <literal>deb</literal> type describes a typical two-level Debian
   archive, <filename>distribution/component</filename>. Typically,
   <literal>distribution</literal> is generally an archivename like
   <literal>stable</literal> or <literal>testing</literal> or a codename like
   <literal>&stable-codename;</literal> or <literal>&testing-codename;</literal>
   while component is one of <literal>main</literal> <literal>contrib</literal> or
   <literal>non-free</literal>. The
   <literal>deb-src</literal> type describes a debian distribution's source
   code in the same form as the <literal>deb</literal> type.
   A <literal>deb-src</literal> line is required to fetch source indexes.</para>


   <para>The format for a <filename>sources.list</filename> entry using the
   <literal>deb</literal> and <literal>deb-src</literal> types is:</para>

   <literallayout>deb [ options ] uri distribution [component1] [component2] [...]</literallayout>

   <para>The URI for the <literal>deb</literal> type must specify the base of the
   Debian distribution, from which APT will find the information it needs. 
   <literal>distribution</literal> can specify an exact path, in which case the 
   components must be omitted and <literal>distribution</literal> must end with
   a slash (/). This is useful for when the case only a particular sub-section of the 
   archive denoted by the URI is of interest.
   If <literal>distribution</literal> does not specify an exact path, at least
   one <literal>component</literal> must be present.</para>

   <para><literal>distribution</literal> may also contain a variable, 
   <literal>$(ARCH)</literal>
   which expands to the Debian architecture (i386, m68k, powerpc, ...)
   used on the system. This permits architecture-independent
   <filename>sources.list</filename> files to be used. In general this is only
   of interest when specifying an exact path, <literal>APT</literal> will
   automatically generate a URI with the current architecture otherwise.</para>

   <para>Since only one distribution can be specified per line it may be necessary
   to have multiple lines for the same URI, if a subset of all available
   distributions or components at that location is desired.
   APT will sort the URI list after it has generated a complete set 
   internally, and will collapse multiple references to the same Internet 
   host, for instance, into a single connection, so that it does not 
   inefficiently establish an FTP connection, close it, do something else, 
   and then re-establish a connection to that same host. This feature is 
   useful for accessing busy FTP sites with limits on the number of 
   simultaneous anonymous users. APT also parallelizes connections to 
   different hosts to more effectively deal with sites with low bandwidth.</para>

   <para><literal>options</literal> is always optional and needs to be surounded by
   square brackets. It can consist of multiple settings in the form
   <literal><replaceable>setting</replaceable>=<replaceable>value</replaceable></literal>.
   Multiple settings are separated by spaces. The following settings are supported by APT,
   note though that unsupported settings will be ignored silently:
   <itemizedlist><listitem><para><literal>arch=<replaceable>arch1</replaceable>,<replaceable>arch2</replaceable>,…</literal>
   can be used to specify for which architectures packages information should
   be downloaded. If this option is not set all architectures defined by the
   <literal>APT::Architectures</literal> option will be downloaded.</para></listitem>
   <listitem><para><literal>trusted=yes</literal> can be set to indicate that packages
   from this source are always authenificated even if the <filename>Release</filename> file
   is not signed or the signature can't be checked. This disables parts of &apt-secure;
   and should therefore only be used in a local and trusted context. <literal>trusted=no</literal>
   is the opposite which handles even correctly authenificated sources as not authenificated.</para></listitem>
   </itemizedlist></para>

   <para>It is important to list sources in order of preference, with the most
   preferred source listed first. Typically this will result in sorting
   by speed from fastest to slowest (CD-ROM followed by hosts on a local
   network, followed by distant Internet hosts, for example).</para>

   <para>Some examples:</para>
   <literallayout>
deb http://ftp.debian.org/debian &stable-codename; main contrib non-free
deb http://security.debian.org/ &stable-codename;/updates main contrib non-free
   </literallayout>

 </refsect1>

 <refsect1><title>URI specification</title>

   <para>The currently recognized URI types are cdrom, file, http, ftp, copy,
   ssh, rsh.
   <variablelist>
    <varlistentry><term>file</term>
    <listitem><para>
    The file scheme allows an arbitrary directory in the file system to be
    considered an archive. This is useful for NFS mounts and local mirrors or
    archives.</para></listitem>
    </varlistentry>
    
    <varlistentry><term>cdrom</term>
    <listitem><para>
    The cdrom scheme allows APT to use a local CDROM drive with media
    swapping. Use the &apt-cdrom; program to create cdrom entries in the
    source list.</para></listitem>
    </varlistentry>

    <varlistentry><term>http</term>
    <listitem><para>
    The http scheme specifies an HTTP server for the archive. If an environment
    variable <envar>http_proxy</envar> is set with the format 
    http://server:port/, the proxy server specified in
    <envar>http_proxy</envar> will be used. Users of authenticated
    HTTP/1.1 proxies may use a string of the format
    http://user:pass@server:port/.
    Note that this is an insecure method of authentication.</para></listitem>
    </varlistentry>

    <varlistentry><term>ftp</term>
    <listitem><para>
    The ftp scheme specifies an FTP server for the archive. APT's FTP behavior
    is highly configurable; for more information see the
    &apt-conf; manual page. Please note that a ftp proxy can be specified
    by using the <envar>ftp_proxy</envar> environment variable. It is possible
    to specify a http proxy (http proxy servers often understand ftp urls)
    using this method and ONLY this method. ftp proxies using http specified in
    the configuration file will be ignored.</para></listitem>
    </varlistentry>

    <varlistentry><term>copy</term>
    <listitem><para>
    The copy scheme is identical to the file scheme except that packages are
    copied into the cache directory instead of used directly at their location.
    This is useful for people using a zip disk to copy files around with APT.</para></listitem>
    </varlistentry>
    
    <varlistentry><term>rsh</term><term>ssh</term>
    <listitem><para>
    The rsh/ssh method invokes rsh/ssh to connect to a remote host
	as a given user and access the files. It is a good idea to do prior
	arrangements with RSA keys or rhosts.
    Access to files on the remote uses standard <command>find</command> and
    <command>dd</command> 
    commands to perform the file transfers from the remote.</para></listitem>
    </varlistentry>

    <varlistentry><term>more recognizable URI types</term>
    <listitem><para>
    APT can be extended with more methods shipped in other optional packages which should
    follow the nameing scheme <literal>apt-transport-<replaceable>method</replaceable></literal>.
    The APT team e.g. maintains also the <literal>apt-transport-https</literal> package which
    provides access methods for https-URIs with features similar to the http method, but other
    methods for using e.g. debtorrent are also available, see <citerefentry>
    <refentrytitle><filename>apt-transport-debtorrent</filename></refentrytitle>
    <manvolnum>1</manvolnum></citerefentry>.
    </para></listitem>
    </varlistentry>
  </variablelist>
 </para>
 </refsect1>
 
 <refsect1><title>Examples</title>
   <para>Uses the archive stored locally (or NFS mounted) at /home/jason/debian
   for stable/main, stable/contrib, and stable/non-free.</para>
   <literallayout>deb file:/home/jason/debian stable main contrib non-free</literallayout>

   <para>As above, except this uses the unstable (development) distribution.</para>
   <literallayout>deb file:/home/jason/debian unstable main contrib non-free</literallayout>

   <para>Source line for the above</para>
   <literallayout>deb-src file:/home/jason/debian unstable main contrib non-free</literallayout>

   <para>The first line gets package information for the architectures in <literal>APT::Architectures</literal>
   while the second always retrieves <literal>amd64</literal> and <literal>armel</literal>.</para>
   <literallayout>deb http://ftp.debian.org/debian &stable-codename; main
deb [ arch=amd64,armel ] http://ftp.debian.org/debian &stable-codename; main</literallayout>

   <para>Uses HTTP to access the archive at archive.debian.org, and uses only
   the hamm/main area.</para>
   <literallayout>deb http://archive.debian.org/debian-archive hamm main</literallayout>

   <para>Uses FTP to access the archive at ftp.debian.org, under the debian
   directory, and uses only the &stable-codename;/contrib area.</para>
   <literallayout>deb ftp://ftp.debian.org/debian &stable-codename; contrib</literallayout>

   <para>Uses FTP to access the archive at ftp.debian.org, under the debian
   directory, and uses only the unstable/contrib area. If this line appears as
   well as the one in the previous example in <filename>sources.list</filename>
   a single FTP session will be used for both resource lines.</para>
   <literallayout>deb ftp://ftp.debian.org/debian unstable contrib</literallayout>

   <para>Uses HTTP to access the archive at ftp.tlh.debian.org, under the
   universe directory, and uses only files found under
   <filename>unstable/binary-i386</filename> on i386 machines,
   <filename>unstable/binary-amd64</filename> on amd64, and so
   forth for other supported architectures. [Note this example only
   illustrates how to use the substitution variable; official debian
   archives are not structured like this]
   <literallayout>deb http://ftp.tlh.debian.org/universe unstable/binary-$(ARCH)/</literallayout>
   </para>
 </refsect1>
 
 <refsect1><title>See Also</title>
   <para>&apt-cache; &apt-conf;
   </para>
 </refsect1>

 &manbugs;
 
</refentry>