21.2.2. Mounting NFS File Systems using autofs

A third option for mounting an NFS share is the use of the autofs service. Autofs uses the automount daemon to manage your mount points by only mounting them dynamically when they are accessed.

Autofs consults the master map configuration file /etc/auto.master to determine which mount points are defined. It then starts an automount process with the appropriate parameters for each mount point. Each line in the master map defines a mount point and a separate map file that defines the file systems to be mounted under this mount point. For example, the /etc/auto.misc file might define mount points in the /misc directory; this relationship would be defined in the /etc/auto.master file.

Each entry in auto.master has three fields. The first field is the mount point. The second field is the location of the map file, and the third field is optional. The third field can contain information such as a timeout value.

For example, to mount the directory /proj52 on the remote machine penguin.example.net at the mount point /misc/myproject on your machine, add the following line to auto.master:

/misc   /etc/auto.misc --timeout 60

Next, add the following line to /etc/auto.misc:

myproject  -rw,soft,intr,rsize=8192,wsize=8192 penguin.example.net:/proj52

The first field in /etc/auto.misc is the name of the /misc subdirectory. This subdirectory is created dynamically by automount. It should not actually exist on the client machine. The second field contains mount options such as rw for read and write access. The third field is the location of the NFS export including the hostname and directory.

To start the autofs service, at a shell prompt, type the following command:

 /sbin/service autofs restart 

To view the active mount points, type the following command at a shell prompt:

 /sbin/service autofs status 

If you modify the /etc/auto.master configuration file while autofs is running, you must tell the automount daemon(s) to reload by typing the following command at a shell prompt:

 /sbin/service autofs reload 

To learn how to configure autofs to start at boot time, and for information on managing services, refer to Chapter 19, Controlling Access to Services.