X-Git-Url: https://git.saurik.com/apt.git/blobdiff_plain/58a642755c63cde3cf377d3719d66add27b13d65..d2cca6ec46865a1f5167f846e67150dc19ca2022:/doc/apt_preferences.5.xml diff --git a/doc/apt_preferences.5.xml b/doc/apt_preferences.5.xml index 54c01100c..f56958fcc 100644 --- a/doc/apt_preferences.5.xml +++ b/doc/apt_preferences.5.xml @@ -1,6 +1,6 @@ - %aptent; @@ -17,7 +17,7 @@ &apt-email; &apt-product; - 16 February 2010 + 2012-06-09T00:00:00Z @@ -45,7 +45,7 @@ the &sources-list; file contains references to more than one distribution APT assigns a priority to each version that is available. Subject to dependency constraints, apt-get selects the version with the highest priority for installation. -The APT preferences file overrides the priorities that APT assigns to +The APT preferences override the priorities that APT assigns to package versions by default, thus giving the user control over which one is selected for installation. @@ -53,26 +53,28 @@ one is selected for installation. the &sources-list; file contains references to more than one source. In this case apt-get downloads the instance listed earliest in the &sources-list; file. -The APT preferences file does not affect the choice of instance, only +The APT preferences do not affect the choice of instance, only the choice of version. Preferences are a strong power in the hands of a system administrator but they can become also their biggest nightmare if used without care! -APT will not questioning the preferences so wrong settings will therefore +APT will not question the preferences, so wrong settings can lead to uninstallable packages or wrong decisions while upgrading packages. -Even more problems will arise if multiply distribution releases are mixed +Even more problems will arise if multiple distribution releases are mixed without a good understanding of the following paragraphs. -Packages included in a specific release aren't tested in and -therefore doesn't always work as expected in older or newer releases or +Packages included in a specific release aren't tested in (and +therefore don't always work as expected in) older or newer releases, or together with other packages from different releases. You have been warned. Note that the files in the /etc/apt/preferences.d directory are parsed in alphanumeric ascending order and need to obey the -following naming convention: The files have no or "pref" -as filename extension and which only contain alphanumeric, hyphen (-), -underscore (_) and period (.) characters - otherwise they will be silently -ignored. +following naming convention: The files have either no or "pref" +as filename extension and only contain alphanumeric, hyphen (-), +underscore (_) and period (.) characters. +Otherwise APT will print a notice that it has ignored a file, unless that +file matches a pattern in the Dir::Ignore-Files-Silently +configuration list - in which case it will be silently ignored. APT's Default Priority Assignments @@ -103,12 +105,16 @@ algorithm to set the priorities of the versions of a package. Assign: priority 1 to the versions coming from archives which in their Release -files are marked as "NotAutomatic: yes" like the debian experimental archive. +files are marked as "NotAutomatic: yes" but not as "ButAutomaticUpgrades: yes" +like the Debian experimental archive. priority 100 -to the version that is already installed (if any). +to the version that is already installed (if any) and to the versions coming +from archives which in their Release files are marked as "NotAutomatic: yes" and +"ButAutomaticUpgrades: yes" like the Debian backports archive since squeeze-backports. + @@ -125,9 +131,10 @@ files are marked as "NotAutomatic: yes" like the debian experimental archive.If the target release has not been specified then APT simply assigns priority 100 to all installed package versions and priority 500 to all -uninstalled package versions, expect versions coming from archives which +uninstalled package versions, except versions coming from archives which in their Release files are marked as "NotAutomatic: yes" - -these versions get the priority 1. +these versions get the priority 1 or priority 100 if it is additionally marked +as "ButAutomaticUpgrades: yes". APT then applies the following rules, listed in order of precedence, to determine which version of a package to install. @@ -178,14 +185,14 @@ and a general form. The specific form assigns a priority (a "Pin-Priority") to one or more -specified packages and specified version or version range. For example, +specified packages with a specified version or version range. For example, the following record assigns a high priority to all versions of -the perl package whose version number begins with "5.8". +the perl package whose version number begins with "&good-perl;". Multiple packages can be separated by spaces. Package: perl -Pin: version 5.8* +Pin: version &good-perl;* Pin-Priority: 1001 @@ -239,11 +246,11 @@ Pin-Priority: 900 The following record assigns a high priority to all package versions belonging to any release whose Archive name is "stable" -and whose release Version number is "3.0". +and whose release Version number is "&stable-version;". Package: * -Pin: release a=stable, v=3.0 +Pin: release a=stable, v=&stable-version; Pin-Priority: 500 @@ -252,6 +259,50 @@ Pin-Priority: 500 +Regular expressions and &glob; syntax + +APT also supports pinning by &glob; expressions, and regular +expressions surrounded by slashes. For example, the following +example assigns the priority 500 to all packages from +experimental where the name starts with gnome (as a &glob;-like +expression) or contains the word kde (as a POSIX extended regular +expression surrounded by slashes). + + + +Package: gnome* /kde/ +Pin: release n=experimental +Pin-Priority: 500 + + + +The rule for those expressions is that they can occur anywhere +where a string can occur. Thus, the following pin assigns the +priority 990 to all packages from a release starting with &ubuntu-codename;. + + + +Package: * +Pin: release n=&ubuntu-codename;* +Pin-Priority: 990 + + + +If a regular expression occurs in a Package field, +the behavior is the same as if this regular expression were replaced +with a list of all package names it matches. It is undecided whether +this will change in the future; thus you should always list wild-card +pins first, so later specific pins override it. + +The pattern "*" in a Package field is not considered +a &glob; expression in itself. + + + + + + + How APT Interprets Priorities @@ -261,30 +312,30 @@ or negative integers. They are interpreted as follows (roughly speaking): -P > 1000 +P >= 1000 causes a version to be installed even if this constitutes a downgrade of the package -990 < P <=1000 +990 <= P < 1000 causes a version to be installed even if it does not come from the target release, unless the installed version is more recent -500 < P <=990 +500 <= P < 990 causes a version to be installed unless there is a version available belonging to the target release or the installed version is more recent -100 < P <=500 +100 <= P < 500 causes a version to be installed unless there is a version available belonging to some other distribution or the installed version is more recent -0 < P <=100 +0 < P < 100 causes a version to be installed only if there is no installed version of the package @@ -306,7 +357,7 @@ records presented earlier: Package: perl -Pin: version 5.8* +Pin: version &good-perl;* Pin-Priority: 1001 Package: * @@ -322,8 +373,8 @@ Pin-Priority: 50 The most recent available version of the perl package will be installed, so long as that version's version number begins -with "5.8". If any 5.8* version of perl is -available and the installed version is 5.9*, then perl will be +with "&good-perl;". If any &good-perl;* version of perl is +available and the installed version is &bad-perl;*, then perl will be downgraded. A version of any package other than perl that is available from the local system has priority over other versions, @@ -409,17 +460,17 @@ Pin: release n=&testing-codename; the Version: line names the release version. For example, the -packages in the tree might belong to Debian GNU/Linux release -version 3.0. Note that there is normally no version number for the +packages in the tree might belong to Debian release +version &stable-version;. Note that there is normally no version number for the testing and unstable distributions because they have not been released yet. Specifying this in the APT preferences file would require one of the following lines. -Pin: release v=3.0 -Pin: release a=stable, v=3.0 -Pin: release 3.0 +Pin: release v=&stable-version; +Pin: release a=stable, v=&stable-version; +Pin: release &stable-version;