18.2. Mounting a File System

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To attach a certain file system, use the mount command in the following form:
mount [option] device directory
The device can be identified by a full path to a block device (for example, /dev/sda3), a universally unique identifier (UUID; for example, UUID=34795a28-ca6d-4fd8-a347-73671d0c19cb), or a volume label (for example, LABEL=home). Note that while a file system is mounted, the original content of the directory is not accessible.


Linux does not prevent a user from mounting a file system to a directory with a file system already attached to it. To determine whether a particular directory serves as a mount point, run the findmnt utility with the directory as its argument and verify the exit code:
findmnt directory; echo $?
If no file system is attached to the directory, the above command returns 1.
When the mount command is run without all required information (that is, without the device name, the target directory, or the file system type), it reads the content of the /etc/fstab configuration file to see if the given file system is listed. This file contains a list of device names and the directories in which the selected file systems should be mounted, as well as the file system type and mount options. Because of this, when mounting a file system that is specified in this file, you can use one of the following variants of the command:
mount [option] directory
mount [option] device
Note that permissions are required to mount the file systems unless the command is run as root (see Section 18.2.2, “Specifying the Mount Options”).


To determine the UUID and, if the device uses it, the label of a particular device, use the blkid command in the following form:
blkid device
For example, to display information about /dev/sda3, type:
~]# blkid /dev/sda3
/dev/sda3: LABEL="home" UUID="34795a28-ca6d-4fd8-a347-73671d0c19cb" TYPE="ext3"

18.2.1. Specifying the File System Type

In most cases, mount detects the file system automatically. However, there are certain file systems, such as NFS (Network File System) or CIFS (Common Internet File System), that are not recognized, and need to be specified manually. To specify the file system type, use the mount command in the following form:
mount -t type device directory
Table 18.1, “Common File System Types” provides a list of common file system types that can be used with the mount command. For a complete list of all available file system types, consult the relevant manual page as referred to in Section 18.4.1, “Manual Page Documentation”.
Table 18.1. Common File System Types
Type Description
ext2 The ext2 file system.
ext3 The ext3 file system.
ext4 The ext4 file system.
iso9660 The ISO 9660 file system. It is commonly used by optical media, typically CDs.
nfs The NFS file system. It is commonly used to access files over the network.
nfs4 The NFSv4 file system. It is commonly used to access files over the network.
udf The UDF file system. It is commonly used by optical media, typically DVDs.
vfat The FAT file system. It is commonly used on machines that are running the Windows operating system, and on certain digital media such as USB flash drives or floppy disks.

Example 18.2. Mounting a USB Flash Drive

Older USB flash drives often use the FAT file system. Assuming that such drive uses the /dev/sdc1 device and that the /media/flashdisk/ directory exists, mount it to this directory by typing the following at a shell prompt as root:
~]# mount -t vfat /dev/sdc1 /media/flashdisk
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