If you have an LDAP set-up with unix/linux machines and you want to add OSX into this mix, having users log in with their LDAP credentials but with local home directories on each machine you might run into an interesting problem: your user home directories will likely be under /home but while on a standard OSX install that directory exists, it is the territory of the automounter.

So unless you configure the automounter to do something, the home directory won't be created and things will be generally strange and non-function because OSX really likes to assume the availability of a home directory. Which I think is actually quite reasonable.

This problem can be fixed easily by disabling the automounter for /home in the automounter's configuration file, /etc/auto_master. But, that requires modifying a local file on every machine which may not be ideal. Or at least I think it isn't.

So I asked the internet. And came up with nothing. There are many pages that tell you how to configure it to mount NFS or Samba or AFP shares, but none to tell you how it is disabled. 

The answer was hidden away somewhere at the bottom of the man page for auto_master:

-null This map has no entries. It is used to disable entries that occur later in the auto_master file.

That works, because the auto_master and auto_home default configurations are to check in the directory service first and if there are multiple entries for the same thing, the first match is used. So if you set a mount to "-null" in there, anything with the same mount point after it is ignored. So here's what I stuck in my LDAP server to tell the automounter to leave /home alone:

dn: automountMapName=auto_master,dc=poop,dc=nl
objectClass: top
objectClass: automountMap
automountMapName: auto_master

dn: automountKey=/home,automountMapName=auto_master,dc=poop,dc=nl
objectClass: top
objectClass: automount
automountKey: /home
automountInformation: -null

That is, one auto_master container, containing one key for /home which is set to "-null".