List a NFS server shared paths

showmount -e <nfs_server>

Mount/unmount a distant NFS path on Mac OS X

sudo mount_nfs -P home_apache 
sudo umount home_apache

NFS Server on Mac OS X

Slashes in the shared path must be protected by two anti-slashes.

# share /Users/jerome/projects/www/test
sudo nicl . -create /exports/\\/Users\\/jerome\\/projects\\/www

# restrict to computer
sudo nicl . -append /exports/\\/Users\\/jerome\\/projects\\/www clients ""

# changes will be done as jerome
sudo nicl . -append /exports/\\/Users\\/jerome\\/projects\\/www opts "mapall=jerome"

# kill mountd
sudo kill -1 `cat /var/run/`

# launch daemons
sudo /usr/sbin/mountd
sudo /sbin/nfsd -t -u -n 6

# check it worked
showmount -e

Source: Setup an NFS server on Mac OS X

NFS Server on Ubuntu