[PATCH setup 0/3] Setup replacement for incver_ifdep

[Ken Brown]

On 1/28/2016 12:33 PM, Jon Turney wrote:
> Future work: I can't see any reason why this script now needs an
> independent existence, so it could be absorbed by the info package.

That's fine with me.  There will be a new version of texinfo soon (it's 
currently in pretest), so we can make the transition then.  But I need 
to understand the script before I take it over, and I'm confused by the 
command

   install-info $f /usr/share/info/dir ||
   install-info --entry="* $$f ($f): $$f" $$f /usr/share/info/dir

First, what do those double dollar signs mean?

Second, why is the second line needed, i.e., under what circumstances 
would it be expected to succeed after the first install-info command failed?

Thanks.

Ken