NAME<\/a> alternatives \u2212 maintain symbolic links determining default commands<\/p>\n alternatives<\/b> [options<\/i>] –install<\/b> link name path priority<\/i> [–slave<\/b> link name path<\/i>]… [–initscript<\/b> service<\/i>] [–family<\/b> name<\/i>]<\/p>\n alternatives<\/b> [options<\/i>] –remove<\/b> name path<\/i><\/p>\n alternatives<\/b> [options<\/i>] –set<\/b> name path<\/i><\/p>\n alternatives<\/b> [options<\/i>] –auto<\/b> name<\/i><\/p>\n alternatives<\/b> [options<\/i>] –display<\/b> name<\/i><\/p>\n alternatives<\/b> [options<\/i>] –config<\/b> name<\/i><\/p>\n alternatives<\/b> [options<\/i>] –list<\/b><\/p>\n alternatives<\/b> [options<\/i>] –remove-all<\/b> name<\/i><\/p>\n alternatives<\/b> [options<\/i>] –add-slave<\/b> name path slink sname spath<\/i><\/p>\n alternatives<\/b> [options<\/i>] –remove-slave<\/b> name path sname<\/i><\/p>\n alternatives<\/b><\/i> creates, removes, maintains and displays information about the symbolic links comprising the alternatives system. The alternatives system is a reimplementation of the Debian alternatives system. It was rewritten primarily to remove the dependence on perl; it is intended to be a drop in replacement for Debian\u2019s update-dependencies<\/b> script. This man page is a slightly modified version of the man page from the Debian project.<\/p>\n It is possible for several programs fulfilling the same or similar functions to be installed on a single system at the same time. For example, many systems have several text editors installed at once. This gives choice to the users of a system, allowing each to use a different editor, if desired, but makes it difficult for a program to make a good choice of editor to invoke if the user has not specified a particular preference.<\/p>\n The alternatives system aims to solve this problem. A generic name in the filesystem is shared by all files providing interchangeable functionality. The alternatives system and the system administrator together determine which actual file is referenced by this generic name. For example, if the text editors ed<\/b>(1) and nvi<\/b>(1) are both installed on the system, the alternatives system will cause the generic name \/usr\/bin\/editor<\/i> to refer to \/usr\/bin\/nvi<\/i> by default. The system administrator can override this and cause it to refer to \/usr\/bin\/ed<\/i> instead, and the alternatives system will not alter this setting until explicitly requested to do so.<\/p>\n The generic name is not a direct symbolic link to the selected alternative. Instead, it is a symbolic link to a name in the alternatives directory<\/i>, which in turn is a symbolic link to the actual file referenced. This is done so that the system administrator\u2019s changes can be confined within the \/etc<\/i> directory: the FHS (q.v.) gives reasons why this is a Good Thing.<\/p>\n When each package providing a file with a particular functionality is installed, changed or removed, alternatives<\/b> is called to update information about that file in the alternatives system. alternatives<\/b> is usually called from the %post<\/b> or %pre<\/b> scripts in RPM packages.<\/p>\n It is often useful for a number of alternatives to be synchronised, so that they are changed as a group; for example, when several versions of the vi<\/b>(1) editor are installed, the man page referenced by \/usr\/share\/man\/man1\/vi.1<\/i> should correspond to the executable referenced by \/usr\/bin\/vi<\/i>. alternatives<\/b> handles this by means of master<\/i> and slave<\/i> links; when the master is changed, any associated slaves are changed too. A master link and its associated slaves make up a link group<\/i>.<\/p>\n Each link group is, at any given time, in one of two modes: automatic or manual. When a group is in automatic mode, the alternatives system will automatically decide, as packages are installed and removed, whether and how to update the links. In manual mode, the alternatives system will not change the links; it will leave all the decisions to the system administrator.<\/p>\n Link groups are in automatic mode when they are first introduced to the system. If the system administrator makes changes to the system\u2019s automatic settings, this will be noticed the next time alternatives<\/b> is run on the changed link\u2019s group, and the group will automatically be switched to manual mode.<\/p>\n Each alternative has a priority<\/i> associated with it. When a link group is in automatic mode, the alternatives pointed to by members of the group will be those which have the highest priority.<\/p>\n When using the –config<\/i> option, alternatives<\/b> will list all of the choices for the link group of which given name<\/i> is the master link. You will then be prompted for which of the choices to use for the link group. Once you make a change, the link group will no longer be in auto<\/i> mode. You will need to use the –auto<\/i> option in order to return to the automatic state.<\/p>\n Since the activities of alternatives<\/b> are quite involved, some specific terms will help to explain its operation. A name, like \/usr\/bin\/editor<\/i>, which refers, via the alternatives system, to one of a number of files of similar function.<\/p>\n symlink<\/p>\n Without any further qualification, this means a symbolic link in the alternatives directory: one which the system administrator is expected to adjust.<\/p>\n alternative<\/p>\n The name of a specific file in the filesystem, which may be made accessible via a generic name using the alternatives system.<\/p>\n alternatives directory<\/p>\n A directory, by default \/etc\/alternatives<\/i>, containing the symlinks.<\/p>\n administrative directory<\/p>\n A directory, by default \/var\/lib\/alternatives<\/i>, containing alternatives<\/b>\u2019 state information.<\/p>\n link group<\/p>\n A set of related symlinks, intended to be updated as a group.<\/p>\n master link<\/p>\n The link in a link group which determines how the other links in the group are configured.<\/p>\n slave link<\/p>\n A link in a link group which is controlled by the setting of the master link.<\/p>\n automatic mode<\/p>\n When a link group is in automatic mode, the alternatives system ensures that the links in the group point to the highest priority alternatives appropriate for the group.<\/p>\n manual mode<\/p>\n When a link group is in manual mode, the alternatives system will not make any changes to the system administrator\u2019s settings.<\/p>\n Exactly one action must be specified if alternatives<\/b> is to perform any meaningful task. Any number of the common options may be specified together with any action.<\/p>\n COMMON OPTIONS Generate more comments about what alternatives<\/b> is doing.<\/p>\n –quiet<\/b><\/p>\n Don\u2019t generate any comments unless errors occur. This option is not yet implemented.<\/p>\n
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