Lion update removed the 'postgres' user. How to restore it?

Question

I've installed postgres with the kyngchaos installer a couple of months ago. I've now updated to OSX Lion, but the database server fails to start.

A comment on kyngchaos's blog (http://www.kyngchaos.com/blog/2011/20110723_lion) made me look at the 'postgres' user: it doesn't exist anymore! At least, I can't "sudo su postgres" anymore. So I figure that's the reason my server doesn't run.

How can I best restore that user?

Answer 1

(Answering myself)

In the end, the only thing I needed to do was to re-create the "postgres" user. Beforehand, I listed the contents of /usr/local/pgsql/ and saw that for instance the data/ directory was owned by user 101 and group postgres. So I wanted to tie that postgres user to the 101 userid:

sudo dscl . -create /Users/postgres
sudo dscl . -create /Users/postgres UniqueID 101

(And afterwards I restarted my mac as I didn't know how to start that postgres server by hand... ;-)

Answer 2

I think, in your dscl command, rather than doing a -create, you want to do an -append. Apple tends to prefix underbars to daemon usernames. So Apple probably created a _postgres label for user 101. By doing a -create, you're deleting the default _postgres user, and replacing it with postgres, which could cause other problems down the road. Whereas if you do an -append, then you can user either _postgres or postgres to reference user 101. In any event, you should do a -list before doing either a -create or an -append, just so you know the lay of the land.

Note: I'm still running Snow Leopard, so can't verify that user 101 is indeed _postgres, but I expect Apple is still using the same naming conventions as in Leopard & Snow Leopard, and that's how it should work. Doing a -list will show you what you need to know to confirm my suspicions.