LPIC-1 Devices, Filesystems and FHS Practice Test 5 — 15 Questions

Question 1

Refer to the exhibit. A user 'user1' tries to run the setuid binary 'myapp' but gets permission denied. What is the most likely reason?

Accepted Answer

The binary has the setuid bit set, but the filesystem is mounted with 'nosuid'. When a filesystem is mounted with the 'nosuid' option, the kernel ignores setuid and setgid bits on executables within that filesystem. Even if 'myapp' has the setuid bit set, the nosuid mount flag prevents the effective UID from changing to the file owner, so 'user1' still runs the binary with their own privileges and may receive 'Permission denied' if the binary requires root-level access.

Answer

The binary is missing the setgid bit

Answer

The binary is not executable by others

Answer

The user does not belong to the root group

Question 2

Refer to the exhibit. The administrator wants to mount /dev/sdb1 persistently using its UUID. Which line should be added to /etc/fstab?

Accepted Answer

UUID=12345678-1234-1234-1234-123456789abc /mnt/data ext4 defaults 0 2. The /etc/fstab entry must use the full UUID of the filesystem (not the partition) in the format UUID=... followed by the mount point, filesystem type, mount options, dump flag, and fsck order. The UUID uniquely identifies the filesystem regardless of device name changes, making mounts persistent across reboots.

Answer

UUID=abcdef01-02 /mnt/data ext4 defaults 0 2

Answer

/dev/sdb1 /mnt/data ext4 defaults 0 2

Answer

LABEL= /mnt/data ext4 defaults 0 2

Question 3

A Linux administrator notices that the /home filesystem, which is on /dev/sda3, is nearly full. The administrator wants to temporarily mount the filesystem with options that allow the root user to reserve less space for emergency use, but without changing the filesystem's default mount options. Which command will achieve this?

Accepted Answer

tune2fs -m 1 /dev/sda3. The reserved block percentage on ext4 filesystems is controlled by tune2fs -m. By default, 5% of blocks are reserved for root. Reducing this to 1% frees space for regular users. This is a filesystem-level setting, not a mount option. Commands like mount -o remount,reserve are invalid, and resize2fs is for resizing, not for adjusting reserved blocks.

Answer

mount -o remount,reserve=1% /dev/sda3 /home

Answer

mount -o remount,usrquota /dev/sda3 /home

Answer

resize2fs /dev/sda3 1%

Question 4

A technician is troubleshooting a server that fails to boot because the root filesystem cannot be mounted. The /etc/fstab entry for the root device is shown in the exhibit. Which of the following is the most likely cause of the failure?

Accepted Answer

The UUID specified in /etc/fstab does not match the actual UUID of the root filesystem.. The most likely cause is that the UUID in /etc/fstab does not match the actual UUID of the root filesystem. This prevents the kernel from finding the root device, leading to a boot failure. The technician should verify the UUID with blkid and update the fstab entry accordingly.

Answer

The device path /dev/sda1 does not exist because the kernel has assigned the disk a different name.

Answer

The mount options in /etc/fstab include 'noauto', preventing automatic mounting at boot.

Answer

The filesystem type ext4 is not supported by the kernel.

Question 5

An administrator is troubleshooting a server where /home is filling rapidly. They want to identify the largest directories under /home without descending into every file, and they also want to see the total apparent size. Which TWO commands or command constructs accomplish this? (Choose two.)

Accepted Answer

du -h --max-depth=1 /home. Both du -sh /home/* and du -h --max-depth=1 /home aggregate usage at the directory level, which is exactly what is needed to spot the largest directories under /home without enumerating every file. df only reports filesystem totals, ls -lR produces unaggregated file listings, and find -size targets individual large files rather than directory totals.

Answer

df -h /home

Answer

find /home -type f -size +100M

Answer

ls -lR /home

Question 6

An administrator must create an ext4 filesystem on a 4 TB partition intended to hold a very large number of small files. The goal is to minimize inode exhaustion while keeping reasonable performance. Which mkfs.ext4 option best addresses the requirement?

Accepted Answer

mkfs.ext4 -i 4096 /dev/sdb1. Inode exhaustion occurs when the fixed inode pool is consumed before data blocks. The bytes-per-inode ratio controls how many inodes mkfs.ext4 creates; lowering it to 4096 multiplies the available inodes across a 4 TB partition. Setting inode size, usage type, or an arbitrary count does not tune that ratio as directly, making the ratio option the precise fix for a small-file workload.

Answer

mkfs.ext4 -N 20000000 /dev/sdb1

Answer

mkfs.ext4 -T small /dev/sdb1

Answer

mkfs.ext4 -I 128 /dev/sdb1

Question 7

An administrator needs to create a new ext4 filesystem on a 4TB disk partition /dev/sdc1. After running 'mkfs.ext4 /dev/sdc1', the command completes successfully, but the filesystem only uses 2TB. Which of the following is the most likely reason for this limitation?

Accepted Answer

The partition table uses MBR, which limits partition size to 2TB.. The most likely reason is that the partition table is MBR, which limits partitions to 2TB. Even if the disk is larger, the partition can only be 2TB, so the filesystem will only use that space. Using GPT instead of MBR would allow partitions larger than 2TB.

Answer

The ext4 filesystem has a maximum size limit of 2TB.

Answer

The disk has a hardware sector size of 4096 bytes, which limits the filesystem to 2TB.

Answer

The mkfs.ext4 command requires the -O 64bit option to enable large filesystem support.

Question 8

A system administrator notices that the /home directory is running out of space. After running 'df -h', the administrator sees that /dev/sda3 is mounted on /home and is 95% full. To free up space, the administrator wants to find the largest files in /home. Which command should the administrator use to list the top 10 largest files recursively under /home?

Accepted Answer

du -a /home | sort -n -r | head -n 10. The correct command is 'du -a /home | sort -n -r | head -n 10'. This recursively lists all files and directories with their sizes, sorts them in descending order, and displays the top 10. Other options either do not recurse properly, include extra output, or are less reliable.

Answer

ls -lR /home | sort -k5 -n -r | head -n 10

Answer

find /home -type f -printf '%s %p
' | sort -n -r | head -n 10

Answer

find /home -type f -exec ls -l {} \; | sort -k5 -n -r | head -n 10

Question 9

Which of the following commands displays the amount of free disk space on all mounted filesystems in a human-readable format?

Accepted Answer

df -h. The `df -h` command displays disk space usage for all mounted filesystems with sizes in human-readable units (e.g., KB, MB, GB). The `-h` flag converts raw block counts into powers of 1024 with appropriate suffixes, making the output easy to interpret at a glance.

Answer

df -i

Answer

du -sh

Answer

df -T

Question 10

An administrator needs to create a new ext4 filesystem on /dev/sdb1 and wants to reserve 2% of the blocks for the root user. Which command should be used?

Accepted Answer

mkfs.ext4 -m 2 /dev/sdb1. The `-m` flag in `mkfs.ext4` specifies the percentage of filesystem blocks reserved for the root user (superuser). By default, ext4 reserves 5% of blocks; using `-m 2` reduces this to 2%, as required. This command creates a new ext4 filesystem on `/dev/sdb1` with the specified reserved block percentage.

Answer

tune2fs -m 2 /dev/sdb1

Answer

mke2fs -r 2 /dev/sdb1

Answer

mkfs.ext4 -R 2 /dev/sdb1

Question 11

A Linux system has a software RAID1 array /dev/md0 consisting of /dev/sda1 and /dev/sdb1. After replacing a failed disk, the administrator runs 'mdadm --manage /dev/md0 --add /dev/sdc1', but the array remains degraded. Which command should be used to check the status of the array?

Accepted Answer

mdadm --detail /dev/md0. The `mdadm --detail /dev/md0` command displays the current state of the RAID array, including its status (e.g., degraded, active), the number of active and failed devices, and the sync/resync progress. Since the array remains degraded after adding a new disk, this command will show whether the new disk has been properly integrated or if there is an underlying issue, such as a missing or failed component.

Answer

mdadm --examine /dev/sdc1

Answer

mdadm --version

Answer

mdadm --query /dev/md0

Question 12

Which directory in the Filesystem Hierarchy Standard (FHS) contains essential user command binaries that are needed in single-user mode?

Accepted Answer

/bin. The /bin directory contains essential user command binaries (e.g., ls, cp, mv) that are required for system booting and repair in single-user mode. According to the FHS, /bin is intended for commands needed by both the system administrator and users when no other filesystems are mounted, making it critical for single-user mode operations.

Answer

/tmp

Answer

/sbin

Answer

/boot

Question 13

An administrator needs to mount an ISO image file /tmp/image.iso to the directory /mnt/iso. Which command should be used?

Accepted Answer

mount -o loop /tmp/image.iso /mnt/iso. The `-o loop` option tells the mount command to use a loop device, which is required to mount a file (like an ISO image) as if it were a block device. Without the loop option, mount expects a block device path, not a regular file.

Answer

mount -o ro /tmp/image.iso /mnt/iso

Answer

mount -t iso /tmp/image.iso /mnt/iso

Answer

mount /tmp/image.iso /mnt/iso

Question 14

A system is running out of disk space on /var. The administrator finds that /var/log/syslog is 4GB. Which of the following is the best course of action to prevent future issues while keeping recent logs?

Accepted Answer

Configure logrotate to rotate and compress logs daily.. Logrotate is the standard Linux utility for managing log file growth. By configuring it to rotate and compress logs daily, the administrator can automatically archive old logs (e.g., /var/log/syslog.1.gz) and keep only recent entries in the active file, preventing disk space exhaustion without losing historical data.

Answer

Use 'truncate -s 0 /var/log/syslog' to empty the file.

Answer

Configure syslog to stop logging.

Answer

Delete /var/log/syslog and create an empty file.

Question 15

Which THREE of the following commands can be used to display information about block devices?

Accepted Answer

lsblk. lsblk (A) is correct because it reads /sys/block and udev data to list all block devices in a tree, showing names, sizes, types, mountpoints, and major:minor numbers. fdisk -l (C) is correct because it enumerates the partition tables of all detected block devices, printing disk geometry, sector sizes, and partition layouts. blkid (D) is correct because it queries block-device attributes such as UUID, LABEL, and filesystem TYPE from the blkid cache and device superblocks. free (B) is not a block-device tool; it reports RAM and swap usage from /proc/meminfo. ip link (E) is a networking command that lists and manages network interfaces at layer 2, not block devices.

Answer

free

Answer

ip link