dpkg/man/en/dselect.8.sgml

<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN">

<refentry id="dselect.8">
  <refmeta>
    <refentrytitle>dselect</refentrytitle>
    <manvolnum>8</manvolnum>
    <refmiscinfo class='source'>Debian Project</refmiscinfo>
    <refmiscinfo class='manual'>dpkg suite</refmiscinfo>
  </refmeta>

  <refnamediv>
    <refname>dselect</refname>
    <refpurpose>Debian package management frontend</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>dselect</command>
      <arg choice="opt">--admindir <replaceable>directory</replaceable></arg>
      <arg choice="opt">--help</arg>
      <arg choice="opt">--version</arg>
      <group choice="opt">
	<arg choice="plain">--licence</arg>
	<arg choice='plain'>--license</arg>
      </group>
      <arg choice="opt">--expert</arg>
      <arg choice="opt">
	<group choice="plain">
	  <arg choice="plain">--debug</arg>
	  <arg choice="plain">-D</arg>
	</group>
	<replaceable>file</replaceable>
      </arg>

      <arg choice="opt">
        <group choice="plain">
	  <arg choice="plain">--colour</arg>
	  <arg choice="plain">--color</arg>
	</group>
	<replaceable>screenpart</replaceable>:<replaceable><optional>foreground</optional></replaceable>,<replaceable><optional>background</optional></replaceable>:<replaceable><optional>attr<replaceable><optional>+attr+..</optional></replaceable></optional></replaceable>
      </arg>
      <arg choice="opt"><replaceable>action</replaceable></arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>
      <command>dselect</command> is the primary user interface for managing
      packages on a Debian system. At the <command>dselect</command> main menu,
      the system administrator can:
    </para>

    <itemizedlist>
      <listitem>
        <para>
	  Update the list of available package versions
	</para>
      </listitem>

      <listitem>
        <para>
	  View the status of installed and available packages,
	</para>
      </listitem>

      <listitem>
        <para>
	  Alter package selections and manage dependencies,
	</para>
      </listitem>

      <listitem>
        <para>
	  Install new packages or upgrade to newer versions.
	</para>
      </listitem>
    </itemizedlist>


    <para>
      <command>dselect</command> operates as a front-end to
      <command>>dpkg</command>, the medium-level debian package handling tool.
      It features a full-screen package selections manager with package depends
      and conflicts resolver. When run with adminitrator priviledges, packages
      can be installed, upgraded and removed. Various access methods can be
      configured to retrieve available package version information and
      installable packages from package repositories.  Depending on the used
      access method, these repositories can be public archive servers on the
      internet, local archive servers or cdroms.  The recommended access method
      is <emphasis>apt</emphasis>, which is provided by the package
      <productname>apt</productname>.
    </para>

    <para>
      Normally <command>dselect</command> is invoked without parameters.  An
      interactive menu is presented, offering the user a list of actions.  If
      an action is given as argument, then that action is started immediately.
      Several commandline parameters are still available to modify the running
      behaviour of <command>dselect</command> or show additional information
      about the program.
    </para>
  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>
      All options can be specified both on the commandline and in the
      <command>dselect</command> configuration file
      <filename>/etc/dpkg/dselect.cfg</filename>. Each line in the
      configuration file is either an option (exactly the same as the
      commandline option but without leading dashes) or a comment (if it starts
      with a hash `#' sign).
    </para>

    <variablelist>
      <varlistentry>
	<term>
	  <cmdsynopsis>
	    <arg choice="plain">--admindir <replaceable>directory</replaceable></arg>
	  </cmdsynopsis>
	</term>

	<listitem>
	  <para>
	    Changes the directory where the dpkg <filename>status</filename>,
	    <filename>available</filename> and similar files are located. This
	    defaults to <filename>/var/lib/dpkg</filename> and normally there
	    should not be any need to change it.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>
	  <cmdsynopsis>
	    <group choice="plain">
	      <arg choice="plain">--debug <replaceable>file</replaceable></arg>
	      <arg choice="plain">-D <replaceable>file</replaceable></arg>
	    </group>
	  </cmdsynopsis>
	</term>

	<listitem>
	  <para>
	    Turn on debugging. Debugging information is sent to
	    <option>file</option>.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>
	  <cmdsynopsis>
	    <arg choice="plain">--expert</arg>
	  </cmdsynopsis>
	</term>

	<listitem>
	  <para>
	    Turns on expert mode, i.e. does not display possibly annoying
	    help messages.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>
	  <cmdsynopsis>
	    <arg choice="plain">
	      <group choice="plain">
		<arg choice="plain">--colour</arg>
		<arg choice="plain">--color</arg>
	      </group>
	      <replaceable>screenpart</replaceable>:<replaceable><optional>foreground</optional></replaceable>,<replaceable><optional>background</optional></replaceable>:<replaceable><optional>attr<replaceable><optional>+attr+..</optional></replaceable></optional></replaceable>
	    </arg>
	  </cmdsynopsis>
	</term>

	<listitem>
	  <para>
	    Configures screen colours. This works only if your display
	    supports colours. This option may be used multiple times (and is
	    best used in <filename>dselect.cfg</filename>). Each use changes
	    the colour (and optionally, other attributes) of one part of the
	    screen. The parts of the screen (from top to bottom) are:
	  </para>

	  <variablelist>
	    <varlistentry>
	      <term>title</term>

	      <listitem>
		<para>
		  The screen title.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>listhead</term>

	      <listitem>
		<para>
		  The header line above the list of packages.
		</para>
		</listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>list</term>

	      <listitem>
		<para>
		  The scrolling list of packages (and also some help text).
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>listsel</term>

	      <listitem>
		<para>
		  The selected item in the list.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>pkgstate</term>

	      <listitem>
		<para>
		  In the list of packages, the text indicating the current
		  state of each package.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>pkgstatesel</term>

	      <listitem>
		<para>
		  In the list of packages, the text indicating the current
		  state of the currently selected package.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>infohead</term>

	      <listitem>
		<para>
		  The header line that displays the state of the currently
		  selected package.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>infodesc</term>

	      <listitem>
		<para>
		  The package's short description.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>info</term>

	      <listitem>
		<para>
		  Used to display package info such as the package's description.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>infofoot</term>

	      <listitem>
		<para>
		  The last line of the screen when selecting packages.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>query</term>

	      <listitem>
		<para>
		  Used to display query lines.
		</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>helpscreen</term>

	      <listitem>
		<para>
		  Colour of help screens.
		</para>
	      </listitem>
	    </varlistentry>
	  </variablelist>

	  <para>
	    After the part of the screen comes a colon and the color
	    specification. You can specify either the foreground color, the
	    background color, or both, overriding the compiled-in colors. Use
	    standard curses color names.
	  </para>

	  <para>
	    Optionally, after the color specification is another colon, and
	    an attribute specification. This is a list of one or more
	    attributes, separated by plus ("+") characters. Available
	    attributes include (not all of these will work on all terminals):
	    normal, standout, underline, reverse, blink, bright, dim,
	    bold.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>
	  <cmdsynopsis>
	    <arg choice="plain">--help</arg>
	  </cmdsynopsis>
	</term>

	<listitem>
	  <para>
	    Print a brief help text and exit successfully.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>
	  <cmdsynopsis>
	    <group choice="plain">
	      <arg choice="plain">--licence</arg>
	      <arg choice="plain">--license</arg>
	    </group>
	  </cmdsynopsis>
	</term>

	<listitem>
	  <para>
	    Displays the <command>dselect</command> copyright and license
	    information and exits successfully.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>
	  <cmdsynopsis>
	    <arg choice="plain">--version</arg>
	  </cmdsynopsis>
	</term>

	<listitem>
	  <para>
	    Print version information and exit successfully.
	  </para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Usage</title>

    <para>
      When <command>dselect</command> is started interactively, it prompts the
      user with a menu of available actions:
    </para>

    <variablelist>
      <varlistentry>
	<term>Access</term>

	<listitem>
	  <para>
	    Choose and configure an access method to access package repositories.
	  </para>

	  <para>
	    By default, <command>dselect</command> provides several methods such
	    as <emphasis>floppy</emphasis>, <emphasis>harddisk</emphasis> or
	    <emphasis>cdrom</emphasis>, but other packages may provide additional
	    methods, eg. the <emphasis>apt</emphasis> access method provided by
	    the <productname>apt</productname> package or
	    <emphasis>multi_cd</emphasis> by the
	    <productname>dpkg-multicd</productname> package.
	  </para>

	  <note>
	    <para>
	      The use of the <emphasis>apt</emphasis> access method is strongly
	      recommended.
	    </para>
	  </note>
	</listitem>
      </varlistentry>

      <varlistentry>
        <term>Update</term>

	<listitem>
	  <para>
	    Refresh the available packages database.
	  </para>

	  <para>
	    Retrieves a list of available package versions from the package
	    repository, configured for the current access method, and update
	    the dpkg database. The package lists are commonly provided by the
	    repository as files named <filename>Packages</filename> or
	    <filename>Packages.gz</filename>. These files can be generated by
	    repository maintainers, using the program
	    <command>dpkg-scanpackages</command>.  
	  </para>

	  <para>
	    Details of the update action depend on the access method's
	    implementation. Normally the process is straightforward and
	    requires no user interaction.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
        <term>Select</term>

	<listitem>
	  <para>
	    View or manage package selections and dependencies.
	  </para>

	  <para>
	    This is the main function of <command>dselect</command>. In the
	    select screen, the user can review a list of all available and
	    installed packages. When run with administrator privileges, it is
	    also possible to interactively change packages selection state.
	    <command>dselect</command> tracks the implications of these changes
	    to other depending or conflicting packages.
	  </para>

	  <para>
	    When a conflict or failed depends is detected, a dependency
	    resolution subscreen is prompted to the user. In this screen, a
	    list of conflicting or depending packages is shown, and for each
	    package listed, the reason for its listing is shown. The user may
	    apply the suggestions proposed by <command>dselect</command>,
	    override them, or back out all the changes, including the ones that
	    created the unresolved depends or conflicts.
	  </para>

	  <para>
	    The use of the interactive package selections management screen is
	    explained in more detail below.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>Install</term>

	<listitem>
	  <para>
	    Installs selected packages.
	  </para>

	  <para>
	    The configured access method will fetch installable or upgradable
	    packages from the relevant repositories and install these using
	    <command>dpkg</command>.  Depending on the implementation of the
	    access method, all packages can be prefetched before installation,
	    or fetched when needed.  Some access methods may also remove
	    packages that were marked for removal.
	  <para>

	  <para>
	    If an error occurred during install, it is usually advisable to run
	    install again.  In most cases, the problems will disappear or be
	    solved.  If problems persist or the installation performed was
	    incorrect, please investigate into the causes and circumstances,
	    and file a bug in the Debian bug tracking system.  Instructions on
	    how to do this can be found at <ulink
	    url='http://bugs.debian.org/'>http://bugs.debian.org/</ulink> or by
	    reading the documentation for <command>bug</command> or
	    <command>reportbug</command>, if these are installed.
	  <para>

	  <para>
	    Details of the install action depend on the access method's
	    implementation.  The user's attention and input may be required
	    during installation, configuration or removal of packages.  This
	    depends on the maintainer scripts in the package.  Some packages
	    make use of the <productname>>debconf</productname> library,
	    allowing for more flexible or even automated installation setups.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
        <term>Config</term>

	<listitem>
	  <para>
	    Configures any previously installed, but not fully configured packages.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
        <term>Remove</term>

	<listitem>
	  <para>
	    Removes or purges installed packages, that are marked for removal.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
        <term>Quit</term>

	<listitem>
	  <para>
	    Quit <command>dselect</command>.
	  </para>
	  
	  <para>
	    Exits the program with zero (succesful) errorcode.
	  </para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Package Selections Management</title>

    <refsect2>
      <title>Introduction</title>

      <para>
	<command>dselect</command> directly exposes
	the administrator to some of the complexities involved with managing
	large sets of packages with many interdependencies.  For a user who is
	unfamiliar with the concepts and the ways of the debian package
	management system, it can be quite overwhelming.  Although <emphasis
	remap='B'>dselect</emphasis> is aimed at easing package management and
	administration, it is only instrumental in doing so and can not be
	assumed to be a sufficient substitute for administrator skill and
	understanding.  The user is required to be familiar with the concepts
	underlying the Debian packaging system.  In case of doubt, consult the
	<citerefentry><refentrytitle>dpkg</refentrytitle><manvolnum>8</manvolnum></citerefentry>
	manpage and the Debian policy manual.
      </para>

      <para>
	Unless <command>dselect</command> is run in expert or immediate mode, a
	help screen is first displayed when choosing this action from the menu.
	The user is <emphasis>strongly</emphasis> advised to study all of the
	information presented in the online help screens, when one pops up.
	The online help screens can at any time be invoked with the
	<keycap>?</keycap> key.
      </para>
    </refsect2>

    <refsect2>
      <title>Screen Layout</title>

      <para>
	The select screen is by default split in a top and a bottom half.  The
	top half shows a list of packages.  A cursor bar can select an
	individual package, or a group of packages, if applicable, by selecting
	the group header.  The bottom half of the screen shows some details
	about the package currently selected in the top half of the screen.
	The type of detail that is displayed can be varied.
      </para>

      <para>
	Pressing the <keycap>I</keycap> key toggles a full-screen display of
	the packages list, an enlarged view of the package details, or the
	equally split screen.
      </para>
    </refsect2>

    <refsect2>
      <title>Package Details View</title>

      <para>
	The package details view by default shows the extended package
	description for the package that is currently selected in the packages
	status list.  The type of detail can be toggled by pressing the
	<keycap>i</keycap> key. This alternates between:
      </para>

      <itemizedlist>
        <listitem>
	  <para>
	    the extended description
	  </para>
	</listitem>

	<listitem>
	  <para>
	    the control information for the installed version
	  </para>
	</listitem>

	<listitem>
	  <para>
	    the control information for the available version
	  </para>
	</listitem>
      </itemizedlist>

      <para>
	In a dependency resolution screen, there is also the possibility of
	viewing the specific unresolved depends or conflicts related to the
	package and causing it to be listed.
      </para>
    </refsect2>

    <refsect2>
      <title>Packages Status List</title>

      <para>
	The main select screen displays a list of all packages known to the
	debian package management system.  This includes packages installed on
	the system and packages known from the available packages database.  
      </para>

      <para>
	For every package, the list shows the package's status, priority,
	section, installed and available versions, the package name and its
	short description, all in one line.  By pressing the <keycap>V</keycap>
	key, the display of the installed and available version can be toggled
	between on an off. By pressing the <keycap>v</keycap> key, the package
	status display is toggled between verbose and shorthand. Shorthand
	display is the default.
      </para>

      <para>
	The shorthand status indication consists of four parts:  an error flag,
	which should normally be clear, the current status, the last selection
	state and the current selection state.  The first two relate to the
	actual state of the package, the second pair are about the selections
	set by the user.
      </para>

      <para>
        These are the meanings of the shorthand package status indicator codes:
      </para>

      <table>
        <title>Error flags</title>
	<tgroup cols=2>
	  <thead>
	    <row>
	      <entry>Flag</entry>
	      <entry>Description</entry>
	    </row>
	  </thead>

	  <tbody>
	    <row>
	      <entry>empty</entry>
	      <entry>no error</entry>
	    </row>
	    <row>
	      <entry>R</entry>
	      <entry>serious error, needs reinstallation</entry>
	    </row>
	  </tbody>
	</tgroup>
      </table>

      <table>
        <title>Installed state</title>
	<tgroup cols=2>
	  <thead>
	    <row>
	      <entry>Flag</entry>
	      <entry>Description</entry>
	    </row>
	  </thead>

	  <tbody>
	    <row>
	      <entry>empty</entry>
	      <entry>not installed</entry>
	    </row>
	    <row>
	      <entry>*</entry>
	      <entry>fully installed and configured</entry>
	    </row>
	    <row>
	      <entry>-</entry>
	      <entry>not installed but some config files may remain</entry>
	    </row>
	    <row>
	      <entry>U</entry>
	      <entry>unpacked but not yet configured</entry>
	    </row>
	    <row>
	      <entry>C</entry>
	      <entry>half-configured (an error happened)</entry>
	    </row>
	    <row>
	      <entry>I</entry>
	      <entry>half-installed (an error happened)</entry>
	    </row>
	  </tbody>
	</tgroup>
      </table>

      <table>
        <title>Current and requested selsections</title>
	<tgroup cols=2>
	  <thead>
	    <row>
	      <entry>Flag</entry>
	      <entry>Description</entry>
	    </row>
	  </thead>

	  <tbody>
	    <row>
	      <entry>*</entry>
	      <entry>marked for installation or upgrade</entry>
	    </row>
	    <row>
	      <entry>-</entry>
	      <entry>marked for removal, configuration files remain</entry>
	    </row>
	    <row>
	      <entry>=</entry>
	      <entry>on hold: package will not be processed at all</entry>
	    </row>
	    <row>
	      <entry>_</entry>
	      <entry>marked for purge, also remove configuration and data</entry>
	    </row>
	    <row>
	      <entry>n</entry>
	      <entry>package is new and has yet to be marked</entry>
	    </row>
	  </tbody>
	</tgroup>
      </table>
    </refsect2>

    <refsect2>
      <title>Cursor And Screen Movement</title>

      <para>
	The package selection list and the dependency conflict resolution
	screens can be navigated using motion commands mapped to the following
	keys:
      </para>

      <table>
        <title>movement keybindings</title>

	<tgroup cols=2>
	  <thead>
	    <row>
	      <entry>Key(s)</entry>
	      <entry>Action</entry>
	    </row>
	  </thead>

	  <tbody>
	    <row>
	      <entry><keycap>p</keycap>, <keycap>Up</keycap>, <keycap>k</keycap></entry>
	      <entry>move cursor bar up</entry>
	    </row>
	    <row>
	      <entry><keycap>n</keycap>, <keycap>Down</keycap>, <keycap>j</keycap></entry>
	      <entry>move cursor bar down</entry>
	    </row>
	    <row>
	      <entry><keycap>P</keycap>, <keycap>PgUp</keycap>, <keycap>BackSpace</keycap></entry>
	      <entry>scroll list 1 page up</entry>
	    </row>
	    <row>
	      <entry><keycap>N</keycap>, <keycap>PgDn</keycap>, <keycap>Space</keycap></entry>
	      <entry>scroll list 1 page down</entry>
	    </row>
	    <row>
	      <entry><keycap>Ctrl</keycap>-<keycap>p</keycap></entry>
	      <entry>scroll list 1 line up</entry>
	    </row>
	    <row>
	      <entry><keycap>Ctrl</keycap>-<keycap>n</keycap></entry>
	      <entry>scroll list 1 line down</entry>
	    </row>
	    <row>
	      <entry><keycap>t</keycap>, <keycap>Home</keycap></entry>
	      <entry>jump to top of list</entry>
	    </row>
	    <row>
	      <entry><keycap>e</keycap>, <keycap>End</keycap></entry>
	      <entry>jump to end of list</entry>
	    </row>
	    <row>
	      <entry><keycap>u</keycap></entry>
	      <entry>scroll info 1 page up</entry>
	    </row>
	    <row>
	      <entry><keycap>d</keycap></entry>
	      <entry>scroll info 1 page down</entry>
	    </row>
	    <row>
	      <entry><keycap>Ctrl</keycap>-<keycap>u</keycap></entry>
	      <entry>scroll info 1 line up</entry>
	    </row>
	    <row>
	      <entry><keycap>Ctrl</keycap>-<keycap>d</keycap></entry>
	      <entry>scroll info 1 line down</entry>
	    </row>
	    <row>
	      <entry><keycap>B</keycap>, <keycap>Left</keycap></entry>
	      <entry>pan display 1/3 screen left</entry>
	    </row>
	    <row>
	      <entry><keycap>F</keycap>, <keycap>Right</keycap></entry>
	      <entry>pan display 1/3 screen right</entry>
	    </row>
	    <row>
	      <entry><keycap>Ctrl</keycap>-<keycap>b</keycap></entry>
	      <entry>pan display 1 character left</entry>
	    </row>
	    <row>
	      <entry><keycap>Ctrl</keycap>-<keycap>f</keycap></entry>
	      <entry>pan display 1 character right</entry>
	    </row>
	  </tbody>
	</tgroup>
      </table>
    </refsect2>

    <refsect2>
      <title>Searching And Sorting</title>

      <para>
	The list of packages can be searched by package name. This is done by
	pressing <keycap>/</keycap>, and typing a simple search string. The
	string is interpreted as a
	<citerefentry><refentrytitle>regex</refentrytitle><manvolnum>7</manvolnum></citerefentry>
	regular expression. If you add `<emphasis>/d</emphasis>' to the search
	expression, dselect will also search in descriptions. If you add
	`<emphasis>/i</emphasis>' the search will be case insensitive. You may
	combine these two suffixes like this: `<emphasis>'/id'</emphasis>.
	Repeated searching is accomplished by repeatedly pressing the
	<keycap>n</keycap> or <keycap>\</keycap> keys, until the wanted package
	is found. If the search reaches the bottom of the list, it wraps to
	the top and continues searching from there.
      </para>

      <para>
	The list sort order can be varied by pressing the <keycap>o</keycap>
	and <keycap>O</keycap> keys repeatedly. The following nine sort
	orderings can be selected:
      </para>

      <para>
 alphabet          available           status
 priority+section  available+priority  status+priority
 section+priority  available+section   status+section
      </para>

      <para>
	Where not listed above explicitly, alphabetic order is used as the
	final subordering sort key.
      </para>
    </refsect2>

    <refsect2>
      <title>Altering Selections</title>

      <para>
	The requested selection state of individual packages may be altered
	with the following commands:
      </para>

      <table>
        <title>action keybindings</title>

        <tgroup cols=2>
	  <thead>
	    <row>
	      <entry>Key(s)</entry>
	      <entry>Action</entry>
	    </row>
	  </thead>

	  <tbody>
	    <row>
	      <entry><keycap>+</keycap>, <keycap>Insert</keycap></entry>
	      <entry>install or upgrade</entry>
	    </row>
	    <row>
	      <entry><keycap>=</keycap>, <keycap>H</keycap></entry>
	      <entry>hold in present state and version</entry>
	    </row>
	    <row>
	      <entry><keycap>:</keycap>, <keycap>G</keycap></entry>
	      <entry>unhold: upgrade or leave uninstalled</entry>
	    </row>
	    <row>
	      <entry><keycap>-</keycap>, <keycap>Delete</keycap></entry>
	      <entry>remove, but leave configuration and data</entry>
	    </row>
	    <row>
	      <entry><keycap>_</keycap></entry>
	      <entry>remove &amp; purge configuration and data</entry>
	    </row>
	  </tbody>
	</tgroup>
      </table>

      <para>
	When the change request results in one or more unsatisfied depends or
	conflicts, <command>dselect</command> prompts the user with a
	dependency resolution screen. This will be further explained below.
      </para>

      <para>
	It is also possible to apply these commands to groups of package
	selections, by pointing the cursor bar onto a group header.  The exact
	grouping of packages is dependent on the current
	list ordering settings.  
      </para>

      <para>
	Proper care should be taken when altering large groups of selections,
	because this can instantaneously create large numbers of unresolved
	depends or conflicts, all of which will be listed in one dependency
	resolution screen, making them very hard to handle. In practice, only
	hold and unhold operations are useful when applied to groups.
      </para>
    </refsect2>

    <refsect2>
      <title>Resolving Depends And Conflicts</title>

      <para>
	When the change request results in one or more unsatisfied depends or
	conflicts, <command>dselect</command> prompts the user with a
	dependency resolution screen. First however, an informative help
	screen is displayed. 
      </para>

      <para>
	The top half of this screen lists all the packages that will have
	unresolved depends or conflicts, as a result of the requested change,
	and all the packages whose installation can resolve any of these
	depends or whose removal can resolve any of the conflicts.  The bottom
	half defaults to show the depends or conflicts that cause the currently
	selected package to be listed.
      </para>

      <para>
	When the sublist of packages is displayed initially,
	<command>dselect</command> may have already set the requested selection
	status of some of the listed packages, in order to resolve the depends
	of conflicts that caused the dependency resolution screen to be
	displayed.  Usually, it is best to follow up the suggestions made by
	<command>dselect</command>.
      </para>

      <para>
	The listed packages' selection state may be reverted to the original
	settings, as they were before the unresolved depends or conflicts were
	created, by pressing the <keycap>R</keycap> key. By pressing the
	<keycap>D</keycap> key, the automatic suggestions are reset, but the
	change that caused the dependency resolution screen to be prompted is
	kept as requested.  Finally, by pressing <keycap>U</keycap>, the
	selections are again set to the automatic suggestion values.
      </para>
    </refsect2>

    <refsect2>
      <title>Establishing The Requested Selections</title>

      <para>
	By pressing <keycap>Enter</keycap>, the currently displayed set of
	selections is accepted. If <command>dselect</command> detects no
	unresolved depends as a result of the requested selections, the new
	selections will be set. However, if there are any unresolveded
	depends, <command>dselect</command> will again prompt the user with a
	dependency resolution screen.  
      </para>

      <para>
	To alter a set of selections that creates unresolved depends or
	conflicts and forcing <command>dselect</command> to accept it, press
	the <keycap>Q</keycap> key. This sets the selections as specified by
	the user, unconditionally. Generally, don't do this unless you've read
	the fine print.
      </para>

      <para>
	The opposite effect, to back out any selections change requests and go
	back to the previous list of selections, is attained by pressing the
	<keycap>X</keycap> or <keycap>Escape</keycap> keys. By repeatedly
	pressing these keys, any possibly detrimental changes to the requested
	package selections can be backed out completely to the last established
	settings.
      </para>
    </refsect2>
  </refsect1>

  <refsect1>
    <title>Bugs</title>

    <para>
      The <command>dselect</command> package selection interface is confusing
      to some new users. Reportedly, it even makes seasoned kernel developers
      cry.
    </para>

    <para>
      The documentation is lacking.
    </para>

    <para>
      There is no help option in the main menu.
    </para>

    <para>
      The visible list of available packages cannot be reduced.
    </para>

    <para>
      The built in access methods can no longer stand up to current quality
      standards. Use the access method provided by
      <productname>apt</productname>, it is not only not broken, it is also
      much more flexible than the built in access methods.
    </para>
  </refsect1>

  <refsect1>
    <title>See Also</title>

    <para>
      <citerefentry>
        <refentrytitle>dselect.cfg</refentrytitle>
	<manvolnum>5</manvolnum>
      </citerefentry>,

      <citerefentry>
        <refentrytitle>dpkg</refentrytitle>
	<manvolnum>8</manvolnum>
      </citerefentry>,

      <citerefentry>
	<refentrytitle>apt-get</refentrytitle>
	<manvolnum>8</manvolnum>
      </citerefentry>,

      <citerefentry>
        <refentrytitle>sources.list</refentrytitle>
	<manvolnum>5</manvolnum>
      </citerefentry>,

      <citerefentry>
        <refentrytitle>deb</refentrytitle>
	<manvolnum>5</manvolnum>
      </citerefentry>,

      the Debian policy manual.
    </para>
  </refsect1>
</refentry>