mount and umount in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of the mount command after mounting a USB drive?

You run the command sudo mount /dev/sdb1 /mnt/usb to mount a USB drive. Then you run mount | grep /mnt/usb. What output do you expect?

Linux CLI

sudo mount /dev/sdb1 /mnt/usb
mount | grep /mnt/usb

A No output

B /mnt/usb on /dev/sdb1 type vfat (rw,nosuid,nodev,noexec,relatime,uhelper=udisks2)

C mount: /mnt/usb: special device /dev/sdb1 does not exist

D /dev/sdb1 on /mnt/usb type vfat (rw,nosuid,nodev,noexec,relatime,uhelper=udisks2)

💡 Hint

Remember the output format of the mount command shows device first, then mount point.

The mount command output lists the device first, then the mount point, followed by the filesystem type and options. So the correct output shows /dev/sdb1 on /mnt/usb.

💻 Command Output

intermediate

What error occurs when unmounting a busy mount point?

You try to unmount a mounted directory with sudo umount /mnt/usb but the directory is in use by a process. What error message will you see?

Linux CLI

sudo umount /mnt/usb

A umount: /mnt/usb: target is busy.

B umount: /mnt/usb: no such file or directory.

C umount: /mnt/usb: device not mounted.

D umount: /mnt/usb: permission denied.

💡 Hint

Think about what happens if a directory is open or used by a program when you try to unmount it.

If the mount point is busy (used by a process), umount will refuse and show 'target is busy' error.

📝 Syntax

advanced

Which command correctly mounts a device with read-only option?

You want to mount /dev/sdc1 to /media/backup with read-only access. Which command is correct?

A sudo mount -o ro /dev/sdc1 /media/backup

B sudo mount -ro /dev/sdc1 /media/backup

C sudo mount /media/backup /dev/sdc1 -o ro

D sudo mount /dev/sdc1 /media/backup -o ro

💡 Hint

The options must come immediately after mount command and before device and mount point.

The correct syntax places options right after mount command: mount -o ro device mountpoint.

🚀 Application

advanced

How to safely unmount all USB drives mounted under /media?

You want to unmount all USB drives currently mounted under /media. Which command sequence will do this safely?

A sudo umount /media/*

B mount | grep '/media' | awk '{print $3}' | xargs -r sudo umount

C sudo umount $(mount | grep '/media' | cut -d' ' -f1)

D mount | grep '/media' | cut -d' ' -f3 | sudo umount

💡 Hint

Think about extracting mount points and passing them safely to umount.

Option B extracts mount points (3rd column) under /media and passes them to umount via xargs safely. Others either use wrong fields or wrong syntax.

🧠 Conceptual

expert

What happens if you mount a device on a non-empty directory?

You mount /dev/sdd1 on /mnt/data, but /mnt/data already contains files. What is the effect on those files?

A The mount command will fail with an error about non-empty directory.

B The existing files are merged with the mounted device's files.

C The existing files become hidden and inaccessible until the device is unmounted.

D The existing files are deleted automatically to allow mounting.

💡 Hint

Think about how mounting overlays the mount point directory.

Mounting a device on a non-empty directory hides the original files temporarily. They reappear after unmounting.