Most Linux file systems are mounted at boot and remain mounted while the system is running. This is also true of any remote file systems that have been configured in the
fstab file. However, there may be times when you prefer to have a remote file system mount only on demand—for example, to boost performance by reducing network bandwidth usage, or to hide or obfuscate certain directories for security reasons. The package autofs provides this feature. In this article, I'll describe how to get a basic automount configuration up and running.
First, a few assumptions: Assume the NFS server named
tree.mydatacenter.net is up and running. Also assume a data directory named
ourfiles and two user directories, for Carl and Sarah, are being shared by this server.
A few best practices will make things work a bit better: It is a good idea to use the same user ID for your users on the server and any client workstations where they have an account. Also, your workstations and server should have the same domain name. Checking the relevant configuration files should confirm.
alan@workstation1:~$ sudo getent passwd carl sarah [sudo] password for alan: carl:x:1020:1020:Carl,,,:/home/carl:/bin/bash sarah:x:1021:1021:Sarah,,,:/home/sarah:/bin/bash alan@workstation1:~$ sudo getent hosts 127.0.0.1 localhost 127.0.1.1 workstation1.mydatacenter.net workstation1 10.10.1.5 tree.mydatacenter.net tree
As you can see, both the client workstation and the NFS server are configured in the
hosts file. I’m assuming a basic home or even small office network that might lack proper internal domain name service (i.e., DNS).
Install the packages
You need to install only two packages:
nfs-common for NFS client functions, and
autofs to provide the automount function.
alan@workstation1:~$ sudo apt-get install nfs-common autofs
You can verify that the autofs files have been placed in the
alan@workstation1:~$ cd /etc; ll auto* -rw-r--r-- 1 root root 12596 Nov 19 2015 autofs.conf -rw-r--r-- 1 root root 857 Mar 10 2017 auto.master -rw-r--r-- 1 root root 708 Jul 6 2017 auto.misc -rwxr-xr-x 1 root root 1039 Nov 19 2015 auto.net* -rwxr-xr-x 1 root root 2191 Nov 19 2015 auto.smb* alan@workstation1:/etc$
Now you need to edit several of these files and add the file
auto.home. First, add the following two lines to the file
/mnt/tree /etc/auto.misc /home/tree /etc/auto.home
Each line begins with the directory where the NFS shares will be mounted. Go ahead and create those directories:
alan@workstation1:/etc$ sudo mkdir /mnt/tree /home/tree
Second, add the following line to the file
ourfiles -fstype=nfs tree:/share/ourfiles
This line instructs autofs to mount the
ourfiles share at the location matched in the
auto.master file for
auto.misc. As shown above, these files will be available in the directory
Third, create the file
auto.home with the following line:
* -fstype=nfs tree:/home/&
This line instructs autofs to mount the users share at the location matched in the
auto.master file for
auto.home. In this case, Carl and Sarah's files will be available in the directories
/home/tree/sarah, respectively. The asterisk (referred to as a wildcard) makes it possible for each user's share to be automatically mounted when they log in. The ampersand also works as a wildcard representing the user's directory on the server side. Their home directory should be mapped accordingly in the
passwd file. This doesn’t have to be done if you prefer a local home directory; instead, the user could use this as simple remote storage for specific files.
Finally, restart the
autofs daemon so it will recognize and load these configuration file changes.
alan@workstation1:/etc$ sudo service autofs restart
If you change to one of the directories listed in the file
auto.master and run the
ls command, you won’t see anything immediately. For example, change directory
/mnt/tree. At first, the output of
ls won’t show anything, but after running
cd ourfiles, the
ourfiles share directory will be automatically mounted. The
cd command will also be executed and you will be placed into the newly mounted directory.
carl@workstation1:~$ cd /mnt/tree carl@workstation1:/mnt/tree$ ls carl@workstation1:/mnt/tree$ cd ourfiles carl@workstation1:/mnt/tree/ourfiles$
To further confirm that things are working, the
mount command will display the details of the mounted share.
carl@workstation1:~$ mount tree:/mnt/share/ourfiles on /mnt/tree/ourfiles type nfs4 (rw,relatime,vers=4.0,rsize=131072,wsize=131072,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=10.10.1.22,local_lock=none,addr=10.10.1.5)
/home/tree directory will work the same way for Carl and Sarah.
I find it useful to bookmark these directories in my file manager for quicker access.