Basic AutoFS configuration

AutoFS is an automounter of storage devices for Linux and UNIX operating systems. An automounter enables the user to mount a directory only whenever is needed e.g. when it needs to get accessed. After some time of inactivity, the filesystem will be unmounted. The main automounter’s file is /etc/auto.master (or auto_master sometimes, mainly in Solaris).

/misc	        /etc/auto.misc
/net		-hosts
+auto.master

The interesting parts are the two first entries. The first part of the entry specifies the root directory which autofs will use for the mount points. The second part specifies which file contains the mount points information. For instance, look at the second entry. The /net directory will be used as the root directory and /etc/hosts will be used as the file which contains the mount points information. That means, autofs will make available all the NFS exports of the all hosts specified in /etc/hosts under /net.

Let’s say now that you want to mount when needed, specific NFS exports from your file server. Let’s say that you want to mount them under /mount/nfs. At first place, you’ll need to create the file that will contains the information of the mount points. The file could be /etc/nfstab or whatever you like. You can specify the entries in the following easy understandable format:

music	-rw			192.168.1.10:/exports/music
photos	-ro			192.168.1.10:/exports/photos
apps    -rw,nosuid 	        192.168.1.10:/exports/apps

If you want, you don’t specify any options or specify as many as you need. The options that apply on ‘mount’, apply on AutoFs as well. Once you have created the list file, you need to add in /etc/auto.master and it should then look like this:

/misc			/etc/auto.misc
/net			-hosts
/mount/nfs	 	/etc/nfstab
+auto.master

You can use the automounter in order to mount non-network filesystems.
Next step is to restart autofs daemon. Having done so, you should be able to access the three shares. Note that they may not be displayed under the directory unless you try to access them.

Having a look in /etc/auto.misc gives a few examples:

cd      -fstype=iso9660,ro,nosuid,nodev	:/dev/cdrom

This will mount the CD/DVD drive under /misc when the user, or a service, will try to access it.

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