Master Linux mount & umount: 15 Real‑World Examples and Tips

After inserting a new hard disk, administrators typically create partitions with fdisk or parted, format them with mkfs, and then mount the resulting filesystem. This article explains the mount and umount utilities through fifteen practical examples.

1. Mount a CD-ROM

CD devices appear under /dev. The following command mounts a read‑only CD‑ROM: # mount -t iso9660 -o ro /dev/cdrom /mnt Ensure the target directory ( /mnt) exists before mounting.

2. List all mounted filesystems

Running mount without arguments displays every active mount. After plugging a USB drive, the output shows the device, mount point, filesystem type and options. # mount You can also use df to see space usage for each mount point.

# df
Filesystem     1K-blocks      Used Available Use% Mounted on
/dev/sda5   195069136 128345036  56958520  70% /
...

3. Mount all filesystems listed in /etc/fstab

The /etc/fstab file defines filesystems to be mounted at boot. To (re)mount every entry, use the -a option: # mount -a Typical /etc/fstab entries:

# cat /etc/fstab
proc            /proc           proc    nodev,noexec,nosuid 0 0
/dev/sda5       /               ext4    errors=remount-ro   0 1
/dev/sda6       /mydata         ext2    defaults            0 2
/dev/sda7       /backup         vfat    defaults            0 3

Unmounting all entries can be done with umount -a.

4. Mount a specific filesystem from /etc/fstab

If you provide only a directory name, mount searches /etc/fstab for a matching entry and mounts it: # mount /mydata Attempting to mount the same entry again yields an “already mounted” error.

5. List mounts of a particular type

Use -t together with -l to filter by filesystem type:

# mount -l -t ext2
/dev/sda6 on /mydata type ext2 (rw)

# mount -l -t ext4
/dev/sda5 on / type ext4 (rw,errors=remount-ro)

6. Mount a floppy disk

Floppy devices are also under /dev. Example:

# mount /dev/fd0 /mnt
# cd /mnt

After use, unmount with umount /mnt.

7. Bind‑mount a directory to a new location

The -B option creates an additional mount point that references the same filesystem: # mount -B /mydata /mnt Verification:

# mount | grep /mydata
/dev/sda6 on /mydata type ext2 (rw)
/mydata on /mnt type none (rw,bind)

Changes made under either path are reflected in the other.

8. Move a mount point to another directory

Using -M, you can relocate an existing mount tree: # mount -M /mydata /mnt/ After the move, the original mount point no longer appears.

9. Mount without writing to /etc/mtab

The -n option performs a mount that does not record an entry in /etc/mtab: # mount -n /dev/sda6 /mydata Consequently, mount | grep /mydata and cat /etc/mtab | grep /mydata show nothing.

10. Mount read‑only or read‑write

Read‑only can be requested with -r (alias of -o ro). For ext4 you may also need ro,noload to prevent writes on a dirty filesystem:

# mount /dev/sda6 /mydata -r
# mount /dev/sda6 /mydata -t ext4 -o ro,noload

Read‑write is the default; you can explicitly use -w if desired.

11. Remount an already mounted filesystem

To change mount options of an existing mount, use the remount option: # mount -o remount,rw /mydata Afterwards the mount shows (rw) instead of (ro,noload).

12. Mount an ISO image

Loop‑mount an ISO file to a directory:

# mount -t iso9660 -o loop pdf_collections.iso /mnt

Now the contents of the ISO are accessible under /mnt.

13. Unmount multiple mount points at once

Provide several targets to umount in a single command:

# umount /mydata /backup

14. Lazy unmount

The -l (lazy) option detaches the filesystem immediately but delays cleanup until all references are closed:

# umount -l /mydata

15. Force unmount

If a device is busy, -f forces the unmount (use with caution): # umount -f /mnt When -f fails, you can identify the holding processes with ps or fuser and terminate them before retrying.