Maybe I forgot to click on some half-hidden checkbox when I’ve installed it, but I’ve found out that my Mathematica 9 copy was working only for one of the users in my MacBook. That is annoying, because I keep separate users for my everyday usage, and for giving presentations and classes (so there is zero risk that one of my friends suddenly appears on Skype telling a dirty joke in the middle of a presentation to the Schools’ president).
But I’ve found out the problem is easy to remediate. There are three folders where Mathematica 9 searches for the license files : $BaseDirectory/Licensing, $InstallationDirectory/Configuration/Licensing, and $UserBaseDirectory/Licensing (open a new Mathematica notebook and type the commands $BaseDirectory, etc. to find out exactly what the paths are in your system). Sure enough, mine was in $UserBaseDirectory/Licensing — meaning it was accessible by just that user.
This simple sequence of commands solved the problem :
$ sudo su
$ mkdir $BaseDirectory
$ mv $UserBaseDirectory/Licensing $BaseDirectory
Again, be sure to substitute the $variables above by the correct paths. I’ve double checked the permissions, and mine were already ok (all users had reading permissions). If it’s not the case for you, try this command :
$ chmod -R a+rX $BaseDirectory
And that is all. (I hope that doesn’t violate any terms, but I can’t see why it would : this kind of Mathematica license is per machine, and even if it were per user, well, both users are the same person, and they are never both “on” at once, isn’t it ?)
I don’t know if this Mathematica single-machine/multi-user license problem (or solution) applies for systems other than Mac OS X — if you find out, I’d be glad to know.