The file that controls what filesystems you wish to export is ``/etc/exports''. Its format is:
directory hostname(options)
the ``(options)'' are optional. For example:
/mnt/export speedy.redhat.com
would allow speedy.redhat.com to mount /mnt/export, but:
/mnt/export speedy.redhat.com(ro)
would just allow speedy to mount /mnt/export read-only.
Each time you change /etc/exports, you need to tell the NFS daemons to examine it for new information. One simple way to accomplish this is to just stop and start the daemons:
/etc/rc.d/init.d/nfs stop /etc/rc.d/init.d/nfs start
The following will also work:
killall -HUP rpc.nfsd rpc.mountd
See the following man pages for more details: nfsd(8), mountd(8), and exports(5). Another good reference is Managing NFS and NIS Services by Hal Stern, published by O'Reilly & Associates.