INITDB problem

OK finally I started the ipc-daemon2 service

(I had to reinstall the last CygWin package)

Now when I try to initialize the data I get this

error:

 

$ initdb -D /usr/share/postgresql/data
The files belonging to this database system will be owned by user "mgonzalez".
This user must also own the server process.

 

The database cluster will be initialized with locale C.

 

Fixing permissions on existing directory /usr/share/postgresql/data... ok
creating directory /usr/share/postgresql/data/base... mkdir: cannot create directory '/usr/share/postgresql/data/base': Permission denied

 

I tried to run this process as the postgres user, however when I do:

password:

su: incorrect password

 

Even if I change the password or left it blank it does not let me switch the user.

 

Please help.

 

Thank you in advanced,