[Unison-hackers] New FAQ posted

[Andrew Schulman]

> Title: I installed the command line version of Unison using the "Install command-line tool" menu option, but the wrong version of Unison is being launched.
> 
> The command-line tool is a very small executable that searches for an existing Unison binary to launch it. If several versions of Unison are present, one cannot predict which one will be launched. It is thus recommended to have only one version of the Unison OS X binary.

Just a comment on this.  Different OSes have different ways of handling the
version problem in Unison.  In Cygwin, we have multiple packages:
unison2.27, unison2.32, etc., each of which provides a different
executable: /usr/bin/unison-2.27, /usr/bin/unison-2.32, etc.  The user can
have one or more of those packages installed at a time.  

To choose which version to run, we use alternatives(8) (or as it's known in
Debian, update-alternatives(8))).  The default priorities for the different
alternatives are set to track the highest installed version.  So if a user
has unison2.27 and unison2.32 installed, then /usr/bin/unison is by default
a symlink to /usr/bin/unison-2.32.  If the user wants something different,
they can either (1) explicitly run a different version, e.g.
/usr/bin/unison-2.27, or (2) use alternatives(8) to change which version
the symlink points to.

Andrew.