Setting PostgreSQL's SHMMAX in Mac OS X 10.5 (Leopard)
If you've ever tried to increase the shared_buffers setting in your postgresql.conf to a value that exceeds the amount of shared memory supported by your operating system kernel, then you'll see an error message like this:
copelco@montgomery:~$ /usr/local/pgsql/bin/postmaster -D /usr/local/pgsql ...