In Linux, devices like hard drives, USBs, CDs, and network storage don’t automatically appear as drive letters (like C:, D: in Windows).
Instead, Linux uses a single directory tree starting from /, and you attach storage devices into this tree using mounting.

Mounting and unmounting are essential for accessing storage devices safely.

What is Mounting? (mount)

Mounting means attaching a storage device to a directory in the Linux filesystem so that you can access its files.

• When you “mount” a device, Linux connects it to a mount point (a directory where the device’s contents will appear).

• Before mounting, the device's files are not accessible.

Example mount command:

sudo mount /dev/sdb1 /mnt

• /dev/sdb1 → the device (USB partition)

• /mnt → mount point directory

After mounting, whatever is stored in /dev/sdb1 becomes visible under /mnt.

Common Mount Points

What is Unmounting? (umount)

Unmounting means safely detaching a storage device from the Linux filesystem tree.

You must unmount a device before removing it physically to avoid:

• Data loss

• File corruption

• Incomplete write operations

Example umount command:

sudo umount /mnt

OR unmount by device name:

sudo umount /dev/sdb1

Why Unmounting Is Important

When files are being written, Linux uses buffers and caches.
If you remove a USB drive without unmounting:

• Files may not be fully written

• The filesystem may become corrupted

• The device may need repair (e.g., fsck)

Checking Mounted Devices

1. Show all mounted devices:

mount

2. Modern and cleaner output:

lsblk

3. View mounted filesystems:

df -h

Mounting with Filesystem Type

Sometimes Linux needs you to specify the filesystem:

sudo mount -t ext4 /dev/sda1 /mnt/data

Common filesystems:

• ext4 (Linux default)

• vfat / fat32 (Windows USB)

• ntfs (Windows drives)

• iso9660 (CD/DVD)

Auto-Mounting Using /etc/fstab

To mount a device automatically at boot:

Edit:

sudo nano /etc/fstab

Example entry:

/dev/sda1   /mnt/data   ext4   defaults   0   2

Forcing Unmount (If device is busy)

If you try to unmount a disk in use:

umount: /mnt: target is busy

You can check what is using it:

lsof | grep /mnt

Force unmount:

sudo umount -f /mnt

Lazy unmount (detach when no longer in use):

sudo umount -l /mnt

In Summary