123

Appendix F

Alternative versions of an interface  

update alternatives

(from old

Packaging Manual)

When several packages all provide different versions of the same program or file it is useful to

have the system select a default, but to allow the system administrator to change it and have

their decisions respected.

For example, there are several versions of the

vi

editor, and there is no reason to prevent all

of them from being installed at once, each under their own name (

nvi

,

vim

or whatever).

Nevertheless it is desirable to have the name

vi

refer to something, at least by default.

If all the packages involved cooperate, this can be done with

update alternatives

.

Each

package

provides

its

own

version

under

its

own

name,

and

calls

update alternatives

in its postinst to register its version (and again in its prerm to

deregister it).

See the man page

update alternatives(8)

for details.

If

update alternatives

does not seem appropriate you may wish to consider using diver 

sions instead.