doc/apt_preferences.5.xml

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   5 <!ENTITY % aptent SYSTEM "apt.ent">
   6 %aptent;
   7
   8 <!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
   9 %aptverbatiment;
  10
  11 ]>
  12
  13 <refentry>
  14
  15  <refentryinfo>
  16    &apt-author.team;
  17    &apt-email;
  18    &apt-product;
  19    <!-- The last update date -->
  20    <date>16 February 2010</date>
  21  </refentryinfo>
  22
  23  <refmeta>
  24    <refentrytitle>apt_preferences</refentrytitle>
  25    <manvolnum>5</manvolnum>
  26    <refmiscinfo class="manual">APT</refmiscinfo>
  27  </refmeta>
  28
  29  <!-- Man page title -->
  30  <refnamediv>
  31     <refname>apt_preferences</refname>
  32     <refpurpose>Preference control file for APT</refpurpose>
  33  </refnamediv>
  34
  35 <refsect1>
  36 <title>Description</title>
  37 <para>The APT preferences file <filename>/etc/apt/preferences</filename>
  38 and the fragment files in the <filename>/etc/apt/preferences.d/</filename>
  39 folder can be used to control which versions of packages will be selected
  40 for installation.</para>
  41
  42 <para>Several versions of a package may be available for installation when
  43 the &sources-list; file contains references to more than one distribution
  44 (for example, <literal>stable</literal> and <literal>testing</literal>).
  45 APT assigns a priority to each version that is available.
  46 Subject to dependency constraints, <command>apt-get</command> selects the
  47 version with the highest priority for installation.
  48 The APT preferences file overrides the priorities that APT assigns to
  49 package versions by default, thus giving the user control over which
  50 one is selected for installation.</para>
  51
  52 <para>Several instances of the same version of a package may be available when
  53 the &sources-list; file contains references to more than one source.
  54 In this case <command>apt-get</command> downloads the instance listed
  55 earliest in the &sources-list; file.
  56 The APT preferences file does not affect the choice of instance, only
  57 the choice of version.</para>
  58
  59 <para>Preferences are a strong power in the hands of a system administrator
  60 but they can become also their biggest nightmare if used without care!
  61 APT will not questioning the preferences so wrong settings will therefore
  62 lead to uninstallable packages or wrong decisions while upgrading packages.
  63 Even more problems will arise if multiply distribution releases are mixed
  64 without a good understanding of the following paragraphs.
  65 Packages included in a specific release aren't tested in and
  66 therefore doesn't always work as expected in older or newer releases or
  67 together with other packages from different releases.
  68 You have been warned.</para>
  69
  70 <para>Note that the files in the <filename>/etc/apt/preferences.d</filename>
  71 directory are parsed in alphanumeric ascending order and need to obey the
  72 following naming convention: The files have no or "<literal>pref</literal>"
  73 as filename extension and which only contain alphanumeric,  hyphen (-),
  74 underscore (_) and period (.) characters.
  75 Otherwise APT will print a notice that it has ignored a file if the file
  76 doesn't match a pattern in the <literal>Dir::Ignore-Files-Silently</literal>
  77 configuration list - in this case it will be silently ignored.</para>
  78
  79 <refsect2><title>APT's Default Priority Assignments</title>
  80
  81 <para>If there is no preferences file or if there is no entry in the file
  82 that applies to a particular version then the priority assigned to that
  83 version is the priority of the distribution to which that version
  84 belongs.  It is possible to single out a distribution, "the target release",
  85 which receives a higher priority than other distributions do by default.
  86 The target release can be set on the <command>apt-get</command> command
  87 line or in the APT configuration file <filename>/etc/apt/apt.conf</filename>.
  88 Note that this has precedence over any general priority you set in the
  89 <filename>/etc/apt/preferences</filename> file described later, but not
  90 over specifically pinned packages.
  91 For example,
  92
  93 <programlisting>
  94 <command>apt-get install -t testing <replaceable>some-package</replaceable></command>
  95 </programlisting>
  96 <programlisting>
  97 APT::Default-Release "stable";
  98 </programlisting>
  99 </para>
 100
 101 <para>If the target release has been specified then APT uses the following
 102 algorithm to set the priorities of the versions of a package.  Assign:
 103
 104 <variablelist>
 105 <varlistentry>
 106 <term>priority 1</term>
 107 <listitem><simpara>to the versions coming from archives which in their <filename>Release</filename>
 108 files are marked as "NotAutomatic: yes" but <emphasis>not</emphasis> as "ButAutomaticUpgrades: yes"
 109 like the debian <literal>experimental</literal> archive.</simpara></listitem>
 110 </varlistentry>
 111
 112 <varlistentry>
 113 <term>priority 100</term>
 114 <listitem><simpara>to the version that is already installed (if any) and to the versions coming
 115 from archives which in their <filename>Release</filename> files are marked as "NotAutomatic: yes" and
 116 "ButAutomaticUpgrades: yes" like the debian backports archive since <literal>squeeze-backports</literal>.
 117 </simpara></listitem>
 118 </varlistentry>
 119
 120 <varlistentry>
 121 <term>priority 500</term>
 122 <listitem><simpara>to the versions that are not installed and do not belong to the target release.</simpara></listitem>
 123 </varlistentry>
 124
 125 <varlistentry>
 126 <term>priority 990</term>
 127 <listitem><simpara>to the versions that are not installed and belong to the target release.</simpara></listitem>
 128 </varlistentry>
 129 </variablelist>
 130 </para>
 131
 132 <para>If the target release has not been specified then APT simply assigns
 133 priority 100 to all installed package versions and priority 500 to all
 134 uninstalled package versions, except versions coming from archives which
 135 in their <filename>Release</filename> files are marked as "NotAutomatic: yes" -
 136 these versions get the priority 1 or priority 100 if it is additionally marked
 137 as "ButAutomaticUpgrades: yes".</para>
 138
 139 <para>APT then applies the following rules, listed in order of precedence,
 140 to determine which version of a package to install.
 141 <itemizedlist>
 142 <listitem><simpara>Never downgrade unless the priority of an available
 143 version exceeds 1000.  ("Downgrading" is installing a less recent version
 144 of a package in place of a more recent version.  Note that none of APT's
 145 default priorities exceeds 1000; such high priorities can only be set in
 146 the preferences file.  Note also that downgrading a package
 147 can be risky.)</simpara></listitem>
 148 <listitem><simpara>Install the highest priority version.</simpara></listitem>
 149 <listitem><simpara>If two or more versions have the same priority,
 150 install the most recent one (that is, the one with the higher version
 151 number).</simpara></listitem>
 152 <listitem><simpara>If two or more versions have the same priority and
 153 version number but either the packages differ in some of their metadata or the
 154 <literal>--reinstall</literal> option is given, install the uninstalled one.</simpara></listitem>
 155 </itemizedlist>
 156 </para>
 157
 158 <para>In a typical situation, the installed version of a package (priority 100)
 159 is not as recent as one of the versions available from the sources listed in
 160 the &sources-list; file (priority 500 or 990).  Then the package will be upgraded
 161 when <command>apt-get install <replaceable>some-package</replaceable></command>
 162 or <command>apt-get upgrade</command> is executed.
 163 </para>
 164
 165 <para>More rarely, the installed version of a package is <emphasis>more</emphasis> recent
 166 than any of the other available versions.  The package will not be downgraded
 167 when <command>apt-get install <replaceable>some-package</replaceable></command>
 168 or <command>apt-get upgrade</command> is executed.</para>
 169
 170 <para>Sometimes the installed version of a package is more recent than the
 171 version belonging to the target release, but not as recent as a version
 172 belonging to some other distribution.  Such a package will indeed be upgraded
 173 when <command>apt-get install <replaceable>some-package</replaceable></command>
 174 or <command>apt-get upgrade</command> is executed,
 175 because at least <emphasis>one</emphasis> of the available versions has a higher
 176 priority than the installed version.</para>
 177 </refsect2>
 178
 179 <refsect2><title>The Effect of APT Preferences</title>
 180
 181 <para>The APT preferences file allows the system administrator to control the
 182 assignment of priorities.  The file consists of one or more multi-line records
 183 separated by blank lines.  Records can have one of two forms, a specific form
 184 and a general form.
 185 <itemizedlist>
 186 <listitem>
 187 <simpara>The specific form assigns a priority (a "Pin-Priority") to one or more
 188 specified packages and specified version or version range.  For example,
 189 the following record assigns a high priority to all versions of
 190 the <filename>perl</filename> package whose version number begins with "<literal>5.8</literal>".
 191 Multiple packages can be separated by spaces.</simpara>
 192
 193 <programlisting>
 194 Package: perl
 195 Pin: version 5.8*
 196 Pin-Priority: 1001
 197 </programlisting>
 198 </listitem>
 199
 200 <listitem><simpara>The general form assigns a priority to all of the package versions in a
 201 given distribution (that is, to all the versions of packages that are
 202 listed in a certain <filename>Release</filename> file) or to all of the package
 203 versions coming from a particular Internet site, as identified by the
 204 site's fully qualified domain name.</simpara>
 205
 206 <simpara>This general-form entry in the APT preferences file applies only
 207 to groups of packages.  For example, the following record assigns a high
 208 priority to all package versions available from the local site.</simpara>
 209
 210 <programlisting>
 211 Package: *
 212 Pin: origin ""
 213 Pin-Priority: 999
 214 </programlisting>
 215
 216 <simpara>A note of caution: the keyword used here is "<literal>origin</literal>"
 217 which can be used to match a hostname. The following record will assign a high priority
 218 to all versions available from the server identified by the hostname "ftp.de.debian.org"</simpara>
 219 <programlisting>
 220 Package: *
 221 Pin: origin "ftp.de.debian.org"
 222 Pin-Priority: 999
 223 </programlisting>
 224 <simpara>This should <emphasis>not</emphasis> be confused with the Origin of a distribution as
 225 specified in a <filename>Release</filename> file.  What follows the "Origin:" tag
 226 in a <filename>Release</filename> file is not an Internet address
 227 but an author or vendor name, such as "Debian" or "Ximian".</simpara>
 228
 229 <simpara>The following record assigns a low priority to all package versions
 230 belonging to any distribution whose Archive name is "<literal>unstable</literal>".</simpara>
 231
 232 <programlisting>
 233 Package: *
 234 Pin: release a=unstable
 235 Pin-Priority: 50
 236 </programlisting>
 237
 238 <simpara>The following record assigns a high priority to all package versions
 239 belonging to any distribution whose Codename is "<literal>&testing-codename;</literal>".</simpara>
 240
 241 <programlisting>
 242 Package: *
 243 Pin: release n=&testing-codename;
 244 Pin-Priority: 900
 245 </programlisting>
 246
 247 <simpara>The following record assigns a high priority to all package versions
 248 belonging to any release whose Archive name is "<literal>stable</literal>"
 249 and whose release Version number is "<literal>3.0</literal>".</simpara>
 250
 251 <programlisting>
 252 Package: *
 253 Pin: release a=stable, v=3.0
 254 Pin-Priority: 500
 255 </programlisting>
 256 </listitem>
 257 </itemizedlist>
 258 </para>
 259
 260 </refsect2>
 261
 262 <refsect2>
 263 <title>How APT Interprets Priorities</title>
 264
 265 <para>
 266 Priorities (P) assigned in the APT preferences file must be positive
 267 or negative integers.  They are interpreted as follows (roughly speaking):
 268
 269 <variablelist>
 270 <varlistentry>
 271 <term>P &gt; 1000</term>
 272 <listitem><simpara>causes a version to be installed even if this
 273 constitutes a downgrade of the package</simpara></listitem>
 274 </varlistentry>
 275 <varlistentry>
 276 <term>990 &lt; P &lt;=1000</term>
 277 <listitem><simpara>causes a version to be installed
 278 even if it does not come from the target release,
 279 unless the installed version is more recent</simpara></listitem>
 280 </varlistentry>
 281 <varlistentry>
 282 <term>500 &lt; P &lt;=990</term>
 283 <listitem><simpara>causes a version to be installed
 284 unless there is a version available belonging to the target release
 285 or the installed version is more recent</simpara></listitem>
 286 </varlistentry>
 287 <varlistentry>
 288 <term>100 &lt; P &lt;=500</term>
 289 <listitem><simpara>causes a version to be installed
 290 unless there is a version available belonging to some other
 291 distribution or the installed version is more recent</simpara></listitem>
 292 </varlistentry>
 293 <varlistentry>
 294 <term>0 &lt; P &lt;=100</term>
 295 <listitem><simpara>causes a version to be installed
 296 only if there is no installed version of the package</simpara></listitem>
 297 </varlistentry>
 298 <varlistentry>
 299 <term>P &lt; 0</term>
 300 <listitem><simpara>prevents the version from being installed</simpara></listitem>
 301 </varlistentry>
 302 </variablelist>
 303 </para>
 304
 305 <para>If any specific-form records match an available package version then the
 306 first such record determines the priority of the package version.
 307 Failing that,
 308 if any general-form records match an available package version then the
 309 first such record determines the priority of the package version.</para>
 310
 311 <para>For example, suppose the APT preferences file contains the three
 312 records presented earlier:</para>
 313
 314 <programlisting>
 315 Package: perl
 316 Pin: version 5.8*
 317 Pin-Priority: 1001
 318
 319 Package: *
 320 Pin: origin ""
 321 Pin-Priority: 999
 322
 323 Package: *
 324 Pin: release unstable
 325 Pin-Priority: 50
 326 </programlisting>
 327
 328 <para>Then:
 329 <itemizedlist>
 330 <listitem><simpara>The most recent available version of the <literal>perl</literal>
 331 package will be installed, so long as that version's version number begins
 332 with "<literal>5.8</literal>".  If <emphasis>any</emphasis> 5.8* version of <literal>perl</literal> is
 333 available and the installed version is 5.9*, then <literal>perl</literal> will be
 334 downgraded.</simpara></listitem>
 335 <listitem><simpara>A version of any package other than <literal>perl</literal>
 336 that is available from the local system has priority over other versions,
 337 even versions belonging to the target release.
 338 </simpara></listitem>
 339 <listitem><simpara>A version of a package whose origin is not the local
 340 system but some other site listed in &sources-list; and which belongs to
 341 an <literal>unstable</literal> distribution is only installed if it is selected
 342 for installation and no version of the package is already installed.
 343 </simpara></listitem>
 344 </itemizedlist>
 345 </para>
 346 </refsect2>
 347
 348 <refsect2>
 349 <title>Determination of Package Version and Distribution Properties</title>
 350
 351 <para>The locations listed in the &sources-list; file should provide
 352 <filename>Packages</filename> and <filename>Release</filename> files
 353 to describe the packages available at that location. </para>
 354
 355 <para>The <filename>Packages</filename> file is normally found in the directory
 356 <filename>.../dists/<replaceable>dist-name</replaceable>/<replaceable>component</replaceable>/<replaceable>arch</replaceable></filename>:
 357 for example, <filename>.../dists/stable/main/binary-i386/Packages</filename>.
 358 It consists of a series of multi-line records, one for each package available
 359 in that directory.  Only two lines in each record are relevant for setting
 360 APT priorities:
 361 <variablelist>
 362 <varlistentry>
 363 <term>the <literal>Package:</literal> line</term>
 364 <listitem><simpara>gives the package name</simpara></listitem>
 365 </varlistentry>
 366 <varlistentry>
 367 <term>the <literal>Version:</literal> line</term>
 368 <listitem><simpara>gives the version number for the named package</simpara></listitem>
 369 </varlistentry>
 370 </variablelist>
 371 </para>
 372
 373 <para>The <filename>Release</filename> file is normally found in the directory
 374 <filename>.../dists/<replaceable>dist-name</replaceable></filename>:
 375 for example, <filename>.../dists/stable/Release</filename>,
 376 or <filename>.../dists/&stable-codename;/Release</filename>.
 377 It consists of a single multi-line record which applies to <emphasis>all</emphasis> of
 378 the packages in the directory tree below its parent.  Unlike the
 379 <filename>Packages</filename> file, nearly all of the lines in a <filename>Release</filename>
 380 file are relevant for setting APT priorities:
 381
 382 <variablelist>
 383 <varlistentry>
 384 <term>the <literal>Archive:</literal> or <literal>Suite:</literal> line</term>
 385 <listitem><simpara>names the archive to which all the packages
 386 in the directory tree belong.  For example, the line
 387 "Archive: stable" or
 388 "Suite: stable"
 389 specifies that all of the packages in the directory
 390 tree below the parent of the <filename>Release</filename> file are in a
 391 <literal>stable</literal> archive.  Specifying this value in the APT preferences file
 392 would require the line:
 393 </simpara>
 394 <programlisting>
 395 Pin: release a=stable
 396 </programlisting>
 397 </listitem>
 398 </varlistentry>
 399
 400 <varlistentry>
 401 <term>the <literal>Codename:</literal> line</term>
 402 <listitem><simpara>names the codename to which all the packages
 403 in the directory tree belong.  For example, the line
 404 "Codename: &testing-codename;"
 405 specifies that all of the packages in the directory
 406 tree below the parent of the <filename>Release</filename> file belong to a version named
 407 <literal>&testing-codename;</literal>.  Specifying this value in the APT preferences file
 408 would require the line:
 409 </simpara>
 410 <programlisting>
 411 Pin: release n=&testing-codename;
 412 </programlisting>
 413 </listitem>
 414 </varlistentry>
 415
 416 <varlistentry>
 417 <term>the <literal>Version:</literal> line</term>
 418 <listitem><simpara>names the release version.  For example, the
 419 packages in the tree might belong to Debian GNU/Linux release
 420 version 3.0.  Note that there is normally no version number for the
 421 <literal>testing</literal> and <literal>unstable</literal> distributions because they
 422 have not been released yet.  Specifying this in the APT preferences
 423 file would require one of the following lines.
 424 </simpara>
 425
 426 <programlisting>
 427 Pin: release v=3.0
 428 Pin: release a=stable, v=3.0
 429 Pin: release 3.0
 430 </programlisting>
 431
 432 </listitem>
 433 </varlistentry>
 434
 435 <varlistentry>
 436 <term>the <literal>Component:</literal> line</term>
 437 <listitem><simpara>names the licensing component associated with the
 438 packages in the directory tree of the <filename>Release</filename> file.
 439 For example, the line "Component: main" specifies that
 440 all the packages in the directory tree are from the <literal>main</literal>
 441 component, which entails that they are licensed under terms listed
 442 in the Debian Free Software Guidelines.  Specifying this component
 443 in the APT preferences file would require the line:
 444 </simpara>
 445 <programlisting>
 446 Pin: release c=main
 447 </programlisting>
 448 </listitem>
 449 </varlistentry>
 450
 451 <varlistentry>
 452 <term>the <literal>Origin:</literal> line</term>
 453 <listitem><simpara>names the originator of the packages in the
 454 directory tree of the <filename>Release</filename> file.  Most commonly, this is
 455 <literal>Debian</literal>.  Specifying this origin in the APT preferences file
 456 would require the line:
 457 </simpara>
 458 <programlisting>
 459 Pin: release o=Debian
 460 </programlisting>
 461 </listitem>
 462 </varlistentry>
 463
 464 <varlistentry>
 465 <term>the <literal>Label:</literal> line</term>
 466 <listitem><simpara>names the label of the packages in the directory tree
 467 of the <filename>Release</filename> file.  Most commonly, this is
 468 <literal>Debian</literal>.  Specifying this label in the APT preferences file
 469 would require the line:
 470 </simpara>
 471 <programlisting>
 472 Pin: release l=Debian
 473 </programlisting>
 474 </listitem>
 475 </varlistentry>
 476 </variablelist>
 477 </para>
 478
 479 <para>All of the <filename>Packages</filename> and <filename>Release</filename>
 480 files retrieved from locations listed in the &sources-list; file are stored
 481 in the directory <filename>/var/lib/apt/lists</filename>, or in the file named
 482 by the variable <literal>Dir::State::Lists</literal> in the <filename>apt.conf</filename> file.
 483 For example, the file
 484 <filename>debian.lcs.mit.edu_debian_dists_unstable_contrib_binary-i386_Release</filename>
 485 contains the <filename>Release</filename> file retrieved from the site
 486 <literal>debian.lcs.mit.edu</literal> for <literal>binary-i386</literal> architecture
 487 files from the <literal>contrib</literal> component of the <literal>unstable</literal>
 488 distribution.</para>
 489 </refsect2>
 490
 491 <refsect2>
 492 <title>Optional Lines in an APT Preferences Record</title>
 493
 494 <para>Each record in the APT preferences file can optionally begin with
 495 one or more lines beginning with the word <literal>Explanation:</literal>.
 496 This provides a place for comments.</para>
 497 </refsect2>
 498 </refsect1>
 499
 500 <refsect1>
 501 <title>Examples</title>
 502 <refsect2>
 503 <title>Tracking Stable</title>
 504
 505 <para>The following APT preferences file will cause APT to assign a
 506 priority higher than the default (500) to all package versions belonging
 507 to a <literal>stable</literal> distribution and a prohibitively low priority to
 508 package versions belonging to other <literal>Debian</literal> distributions.
 509
 510 <programlisting>
 511 Explanation: Uninstall or do not install any Debian-originated
 512 Explanation: package versions other than those in the stable distro
 513 Package: *
 514 Pin: release a=stable
 515 Pin-Priority: 900
 516
 517 Package: *
 518 Pin: release o=Debian
 519 Pin-Priority: -10
 520 </programlisting>
 521 </para>
 522
 523 <para>With a suitable &sources-list; file and the above preferences file,
 524 any of the following commands will cause APT to upgrade to the
 525 latest <literal>stable</literal> version(s).
 526
 527 <programlisting>
 528 apt-get install <replaceable>package-name</replaceable>
 529 apt-get upgrade
 530 apt-get dist-upgrade
 531 </programlisting>
 532 </para>
 533
 534 <para>The following command will cause APT to upgrade the specified
 535 package to the latest version from the <literal>testing</literal> distribution;
 536 the package will not be upgraded again unless this command is given
 537 again.
 538
 539 <programlisting>
 540 apt-get install <replaceable>package</replaceable>/testing
 541 </programlisting>
 542 </para>
 543 </refsect2>
 544
 545  <refsect2>
 546  <title>Tracking Testing or Unstable</title>
 547
 548 <para>The following APT preferences file will cause APT to assign
 549 a high priority to package versions from the <literal>testing</literal>
 550 distribution, a lower priority to package versions from the
 551 <literal>unstable</literal> distribution, and a prohibitively low priority
 552 to package versions from other <literal>Debian</literal> distributions.
 553
 554 <programlisting>
 555 Package: *
 556 Pin: release a=testing
 557 Pin-Priority: 900
 558
 559 Package: *
 560 Pin: release a=unstable
 561 Pin-Priority: 800
 562
 563 Package: *
 564 Pin: release o=Debian
 565 Pin-Priority: -10
 566 </programlisting>
 567 </para>
 568
 569 <para>With a suitable &sources-list; file and the above preferences file,
 570 any of the following commands will cause APT to upgrade to the latest
 571 <literal>testing</literal> version(s).
 572
 573 <programlisting>
 574 apt-get install <replaceable>package-name</replaceable>
 575 apt-get upgrade
 576 apt-get dist-upgrade
 577 </programlisting>
 578 </para>
 579
 580 <para>The following command will cause APT to upgrade the specified
 581 package to the latest version from the <literal>unstable</literal> distribution.
 582 Thereafter, <command>apt-get upgrade</command> will upgrade
 583 the package to the most recent <literal>testing</literal> version if that is
 584 more recent than the installed version, otherwise, to the most recent
 585 <literal>unstable</literal> version if that is more recent than the installed
 586 version.
 587
 588 <programlisting>
 589 apt-get install <replaceable>package</replaceable>/unstable
 590 </programlisting>
 591 </para>
 592 </refsect2>
 593
 594
 595 <refsect2>
 596 <title>Tracking the evolution of a codename release</title>
 597
 598 <para>The following APT preferences file will cause APT to assign a
 599 priority higher than the default (500) to all package versions belonging
 600 to a specified codename of a distribution and a prohibitively low priority to
 601 package versions belonging to other <literal>Debian</literal> distributions,
 602 codenames and archives.
 603 Note that with this APT preference APT will follow the migration of a release
 604 from the archive <literal>testing</literal> to <literal>stable</literal> and
 605 later <literal>oldstable</literal>. If you want to follow for example the progress
 606 in <literal>testing</literal> notwithstanding the codename changes you should use
 607 the example configurations above.
 608
 609 <programlisting>
 610 Explanation: Uninstall or do not install any Debian-originated package versions
 611 Explanation: other than those in the distribution codenamed with &testing-codename; or sid
 612 Package: *
 613 Pin: release n=&testing-codename;
 614 Pin-Priority: 900
 615
 616 Explanation: Debian unstable is always codenamed with sid
 617 Package: *
 618 Pin: release n=sid
 619 Pin-Priority: 800
 620
 621 Package: *
 622 Pin: release o=Debian
 623 Pin-Priority: -10
 624 </programlisting>
 625 </para>
 626
 627 <para>With a suitable &sources-list; file and the above preferences file,
 628 any of the following commands will cause APT to upgrade to the
 629 latest version(s) in the release codenamed with <literal>&testing-codename;</literal>.
 630
 631 <programlisting>
 632 apt-get install <replaceable>package-name</replaceable>
 633 apt-get upgrade
 634 apt-get dist-upgrade
 635 </programlisting>
 636 </para>
 637
 638 <para>The following command will cause APT to upgrade the specified
 639 package to the latest version from the <literal>sid</literal> distribution.
 640 Thereafter, <command>apt-get upgrade</command> will upgrade
 641 the package to the most recent <literal>&testing-codename;</literal> version if that is
 642 more recent than the installed version, otherwise, to the most recent
 643 <literal>sid</literal> version if that is more recent than the installed
 644 version.
 645
 646 <programlisting>
 647 apt-get install <replaceable>package</replaceable>/sid
 648 </programlisting>
 649 </para>
 650 </refsect2>
 651 </refsect1>
 652
 653 <refsect1>
 654 <title>Files</title>
 655   <variablelist>
 656     &file-preferences;
 657   </variablelist>
 658 </refsect1>
 659
 660 <refsect1>
 661 <title>See Also</title>
 662 <para>&apt-get; &apt-cache; &apt-conf; &sources-list;
 663 </para>
 664 </refsect1>
 665
 666  &manbugs;
 667
 668 </refentry>