alternatives-update sync alternatives subsystem state with database: creates nessesary symlinks, deletes old one, fix broken.
Default mode is only sync. But you can also use -o and -i switches for advanced features. Using -obsolete, you can remove ``old-style'' symlinks from /etc/alternatives directory. Program remove only links points to files, controlled by alternatives system. Any other links will be ignored. When you use --ignore, alternatives subsystem will ignore selected candidates when it's made a choice.
For example, you have some packages sub1, sub2 and sub3. All of them have candidates for one alternative and also require some common package. You can place database with all candidates to common package. This allows you to made only update requests from packages. All register/unregister procedures will be done by common package.
OPTIONS
-h, --help
display help screen
-v, --version
display version information
-V, --verbose
verbose program output
-g, --ignore
ignore selected candidates
-o, --obsolete
try to remove obsolete symlinks for selected alternatives
-c, --configname
use name as an alternatives config file
FILES
/etc/altenatives/alternatives.xml - main alternatives config file.