File systems that are shared through the NFS service can be mounted by
using automatic mounting. Autofs, a client-side service, is a file-system structure that provides
automatic mounting. The autofs file system is initialized by automount, which is run
automatically when a system is booted. The automount daemon, automountd, runs continuously, mounting and
unmounting remote directories as necessary.
Whenever a client computer that is running automountd tries to access a remote
file or remote directory, the daemon mounts the remote file system. This remote
file system remains mounted for as long as needed. If the remote file
system is not accessed for a certain period of time, the file system
is automatically unmounted.
Mounting need not be done at boot time, and the user no
longer has to know the superuser password to mount a directory. Users do
not need to use the mount and umount commands. The autofs service mounts and
unmounts file systems as required without any intervention by the user.
Mounting some file hierarchies with automountd does not exclude the possibility of mounting
other hierarchies with mount. A diskless computer must mount / (root), /usr,
and /usr/kvm through the mount command and the /etc/vfstab file.
Task Overview for Autofs Administration and How Autofs Works give more specific information about the autofs service.