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UPDATE-ALTERNATIVES(8)                         System Manager's Manual                         UPDATE-ALTERNATIVES(8)

       alternatives - maintain symbolic links determining default commands

       alternatives  [options]  --install link name path priority [--slave link name path]...  [--initscript service]
       [--family name]

       alternatives [options] --remove name path

       alternatives [options] --set name path

       alternatives [options] --auto name

       alternatives [options] --display name

       alternatives [options] --config name

       alternatives [options] --list name

       alternatives 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's
       update-dependencies  script.  This  man  page  is  a slightly modified version of the man page from the Debian

       It is possible for several programs fulfilling the same or similar functions to be installed on a single  sys‐
       tem  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.

       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 deter‐
       mine  which actual file is referenced by this generic name.  For example, if the text editors ed(1) and nvi(1)
       are both installed on the system, the alternatives system will cause the generic name /usr/bin/editor to refer
       to  /usr/bin/nvi  by default.  The system administrator can override this and cause it to refer to /usr/bin/ed
       instead, and the alternatives system will not alter this setting until explicitly requested to do so.

       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, which in turn is a symbolic link to the actual file referenced.  This is
       done so that the system administrator's changes can be confined within the  /etc  directory:  the  FHS  (q.v.)
       gives reasons why this is a Good Thing.

       When  each package providing a file with a particular functionality is installed, changed or removed, alterna‐
       tives is called to update information about that file in the alternatives  system.   alternatives  is  usually
       called from the %post or %pre scripts in RPM packages.

       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(1)  editor  are  installed,  the   man   page   referenced   by
       /usr/share/man/man1/vi.1  should correspond to the executable referenced by /usr/bin/vi.  alternatives handles
       this by means of master and slave links; when the master is changed, any associated slaves are changed too.  A
       master link and its associated slaves make up a link group.

       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
       order to return to the automatic state.

       Since the activities of alternatives are quite involved, some specific terms will help to explain  its  opera‐

       generic name
              A name, like /usr/bin/editor, which refers, via the alternatives system, to one of a number of files of
              similar function.

              Without any further qualification, this means a symbolic link in the alternatives directory: one  which
              the system administrator is expected to adjust.

              The  name  of  a specific file in the filesystem, which may be made accessible via a generic name using
              the alternatives system.

       alternatives directory
              A directory, by default /etc/alternatives, containing the symlinks.

       administrative directory
              A directory, by default /var/lib/alternatives, containing alternatives' state information.

       link group
              A set of related symlinks, intended to be updated as a group.

       master link
              The link in a link group which determines how the other links in the group are configured.

       slave link
              A link in a link group which is controlled by the setting of the master link.

       automatic mode
              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.

       manual mode
              When  a  link  group is in manual mode, the alternatives system will not make any changes to the system
              administrator's settings.

       Exactly one action must be specified if alternatives is to perform any meaningful task.   Any  number  of  the
       common options may be specified together with any action.

              Generate more comments about what alternatives is doing.

              Don't generate any comments unless errors occur.  This option is not yet implemented.

       --test Don't actually do anything, just say what would be done.  This option is not yet implemented.

       --install link name path priority [--slave slink sname spath] [--initscript service]...
              Add  a  group of alternatives to the system.  name is the generic name for the master link, link is the
              name of its symlink, path is the alternative being introduced for the master link, and priority is  the
              priority  of  the  alternatives group. Higher priorities take precendence if no alternative is manually
              selected.  sname, slink and spath are the generic name, symlink name and alternative for a slave  link,
              and  service  is  the  name  of  any associated initscript for the alternative.  NOTE: --initscript and
              --family are a Red Hat Linux specific options.  Zero or more --slave options, each  followed  by  three
              arguments, may be specified.

              If  the  master  symlink specified exists already in the alternatives system's records, the information
              supplied will be added as a new set of alternatives for the group.  Otherwise,  a  new  group,  set  to
              automatic  mode, will be added with this information.  If the group is in automatic mode, and the newly
              added alternatives' priority is higher than any other installed alternatives for this group,  the  sym‐
              links will be updated to point to the newly added alternatives.

              If  --initscript is used, the alternatives system will manage the initscript associated with the alter‐
              native via chkconfig, registering and unregistering the init script depending on which  alternative  is

              NOTE: --initscript is a Red Hat Linux specific option.

              --family  can be used to group similar alternatives. If the group is in manual mode and the alternative
              currently used is removed, alternatives will try to change links to different one with same family  and
              highest priority.

              NOTE: --family is a Red Hat Linux specific option.

       --remove name path
              Remove an alternative and all of its associated slave links.  name is a name in the alternatives direc‐
              tory, and path is an absolute filename to which name could be linked.  If  name  is  indeed  linked  to
              path,  name will be updated to point to another appropriate alternative, or removed if there is no such
              alternative left.  Associated slave links will be updated or removed, correspondingly.  If the link  is
              not  currently  pointing  to  path, no links are changed; only the information about the alternative is

       --set name path
              The symbolic link and slaves for link group name set to those configured for path, and the  link  group
              is set to manual mode.  This option is not in the original Debian implementation.

       --config name
              Present the user with a configuration menu for choosing the master link and slaves for link group name.
              Once chosen, the link group is set to manual mode.

       --auto name
              Switch the master symlink name to automatic mode.  In the process, this  symlink  and  its  slaves  are
              updated to point to the highest priority installed alternatives.

       --display name
              Display  information  about  the  link  group  of which name is the master link.  Information displayed
              includes the group's mode (auto or manual), which alternative the symlink  currently  points  to,  what
              other alternatives are available (and their corresponding slave alternatives), and the highest priority
              alternative currently installed.

       2      Problems were encountered whilst parsing the command line or performing the action.

       alternatives chatters incessantly about its activities on its standard output  channel.   If  problems  occur,
       alternatives  outputs  error  messages  on  its standard error channel and returns an exit status of 2.  These
       diagnostics should be self-explanatory; if you do not find them so, please report this as a bug.

       If you find a bug, please report it using the Red Hat bug tracking system at

       If you find any discrepancy between the operation of alternatives and this manual page, it is a bug, either in
       the implementation or the documentation; please report it.  Any significant differences between this implemen‐
       tation and Debian's is also a bug and should be reported, unless otherwise noted in this man page.

       alternatives is copyright 2002 Red Hat, Inc..  It is free software; see the GNU General Public Licence version
       2 or later for copying conditions.  There is NO warranty.

       This  manual  page  is copyright 1997/98 Charles Briscoe-Smith and 2002 Red Hat, Inc.  This is free documenta‐
       tion; see the GNU General Public Licence version 2 or later for copying conditions.  There is NO WARRANTY.

       ln(1), FHS, the Filesystem Hierarchy Standard.  alternatives.c chkconfig.c COPYING leveldb.c  leveldb.h  Make‐
       file ntsysv.c ook

                                                   27 January 2001                             UPDATE-ALTERNATIVES(8)