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The etc/fstab file. This etc/fstab Configuration File is primarily used during the boot process as it specifies the directories to be mounted on a running system. Let's take a look at two different versions of this file. First from my Red Hat, actually my CentOS system, which specifies the device file, it could be the partition or even the LABEL. In this case the top-level root directory is actually mounted on a Logical Volume and to simplify the presentation I've copied the fstab file from an Ubuntu system to this system here which shows a UUID, or a universally unique identifier, which represents the partition or device file. The second column is the directory to be mounted. For example, the partition associated with this boot LABEL is mounted on the boot directory. The third column is the filesystem format, which is pretty standard. Ext3 is the third extended filesystem. The fourth column is perhaps more complex. It's how the device is to be mounted. Defaults may seem, may sound simple but it's actually a combination of a lot of options which includes read-write super user and super group ID permissions, in other words you're allowed to set that up on files in that system; device files, executable files, without that you wouldn't be able to create executable files in that filesystem; auto, which is based on what you see in the etc. filesystems configuration file, in other words it looks through these possible formats and tries to match one. No user means the privilege of mounting that filesystem is limited to the root administrative user and async which means that reads and writes can be done asynchronously, in other words they don't have to be done at the same time. As you can see here you may see something other than defaults for the Ubuntu system relatime actually adds one more feature to defaults, in this case it specifies when the date and time on a file is changed based on how it works with the inode. Every file is associated with the inode and that's how it's labeled in the filesystem. The fifth column is generally zero or 1. A 1 in that column means data is automatically saved or dumped back to the partition or filesystem. The sixth column is generally set up as 0, 1, or 2. It's the filesystem check order. The check is for corruption and the top-level root directory is checked first, thus it's given a 1, 2 for other directories, for example in this case the root directory is checked first or the root volume followed by the boot partition and the zero associated with the others means that no other filesystem is checked for corruption. You can supersede settings in etc/fstab by running the mount command with specific options. For example, if something is set up in fstab as Read-only you can supersede it by mounting it as read-write, or you could use an option like ro, which would be Read-only. For more information on available options to the mount command go to the Command Line and run man mount. That's the scoop on the etc/fstab configuration file. Thank you and on to the next video.