LFCS Essential Commands Practice Test 9 — 15 Questions

Question 1

A junior administrator needs to create a symbolic link named /usr/local/bin/editor that points to /opt/tools/vim.bin. The link must be created without overwriting any existing file at the destination. Which command accomplishes this?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

ln -s /opt/tools/vim.bin /usr/local/bin/editor. Creating a symbolic link is done with ln -s target linkname. Because the destination does not exist, no force flag is required and the command completes without overwriting anything. The hard-link variant lacks -s and would not produce a symbolic link, while the forced variant introduces overwrite risk that the scenario explicitly forbids.

Answer

ln /opt/tools/vim.bin /usr/local/bin/editor

Answer

ln -sf /opt/tools/vim.bin /usr/local/bin/editor

Answer

cp -s /opt/tools/vim.bin /usr/local/bin/editor

Question 2

An administrator must change the ownership of /srv/project and every file and directory beneath it to user alice and group devs, without altering permissions. Which command should be used?

Accepted Answer

chown -R alice:devs /srv/project. Changing both owner and group recursively is the job of chown with the -R flag and the user:group syntax. This updates ownership metadata on every file and directory under the target path while leaving permission bits intact. chmod, usermod, and chgrp each address different attributes and cannot fulfill the combined owner-and-group requirement.

Answer

chmod -R alice:devs /srv/project

Answer

chgrp -R alice:devs /srv/project

Answer

usermod -R alice:devs /srv/project

Question 3

A support engineer must copy the directory /srv/appdata, including every subdirectory, hidden file, and preserved permission bits and timestamps, to /backup/appdata on the same host. Which command accomplishes this?

Accepted Answer

cp -a /srv/appdata /backup/appdata. Archive-mode copy is the correct tool when a directory tree must be duplicated with metadata intact, since it combines recursion with preservation of permissions, ownership, timestamps, and symlink structure. Recursive-only copy drops metadata, relocation deletes the source, and a bare rsync invocation without archive or recursive flags will not descend into directories.

Answer

mv /srv/appdata /backup/appdata

Answer

rsync /srv/appdata /backup/appdata

Answer

cp -r /srv/appdata /backup/appdata

Question 4

An administrator needs to change the ownership of the directory /srv/www to user webadmin and group webteam, including all existing files and subdirectories. Which command accomplishes this?

Accepted Answer

chown -R webadmin:webteam /srv/www. The chown command changes file ownership, and the -R flag applies the change recursively. Specifying both user and group as webadmin:webteam in one invocation sets the owner and group for the directory and everything beneath it. This is the standard, efficient way to recursively reassign ownership for a web directory.

Answer

chmod -R webadmin:webteam /srv/www

Answer

usermod -R webadmin:webteam /srv/www

Answer

chown webadmin:webteam /srv/www

Question 5

An administrator runs `ls -l` and sees a file entry whose permission string begins with a lowercase `l`. What does this indicate about the entry?

Accepted Answer

It is a symbolic link whose target is resolved when the link is accessed.. The first character of the permission string encodes file type, and l specifically means symbolic link. Device nodes, regular files, and FIFOs each have their own distinct type character, so recognizing the type column is essential before choosing commands such as readlink, stat, or find -type l.

Answer

It is a named pipe used for inter-process communication.

Answer

It is a regular file that has the setuid bit enabled.

Answer

It is a block device node used for buffered disk access.

Question 6

A support engineer must copy the file /etc/hosts to /tmp/hosts.backup but only if /tmp/hosts.backup does not already exist, so that an existing backup is never overwritten. Which command performs this conditionally?

Accepted Answer

cp --no-clobber /etc/hosts /tmp/hosts.backup. The --no-clobber option makes cp skip the operation entirely when the destination already exists, leaving the existing backup intact while still performing the copy when the destination is absent. The other options either ignore existence altogether, base the decision on timestamps, or rename the old file, all of which still result in the destination being replaced.

Answer

cp --update /etc/hosts /tmp/hosts.backup

Answer

cp --backup /etc/hosts /tmp/hosts.backup

Answer

cp --preserve=all /etc/hosts /tmp/hosts.backup

Question 7

A technician must locate every regular file beneath /var that is larger than 100 MB and was modified more than 30 days ago, then list them. Which TWO find expressions achieve this? (Choose two.)

Accepted Answer

find /var -type f -size +100M -mtime +30 -print. Two variants are correct because find's implicit print makes -print optional, and both retain the -type f, -size +100M, and -mtime +30 tests. Substituting atime measures access rather than modification, dropping the type test admits non-regular entries, and using double-dash predicates is a syntax error that prevents execution.

Answer

find /var -type f -size +100M -atime +30 -print

Answer

find /var -size +100M -mtime +30 -exec ls -l {} \;

Answer

find /var --type f --size +100M --mtime +30 -print

Question 8

A system administrator needs to identify the absolute path of the executable that would be run when typing the command 'ls'. Which command should they use?

Accepted Answer

which ls. The which command is designed to search the PATH and report the full path of the executable that would be run. whereis, locate, and find do not respect the PATH or executable resolution order, so they cannot reliably answer which binary would execute. Thus, which is the correct choice.

Answer

find / -name ls

Answer

whereis ls

Answer

locate ls

Question 9

A security analyst needs to search for the literal string 'error: failed to connect' in all .log files under /var/log, including subdirectories. The search should be case-insensitive and display line numbers. Which command should they use?

Accepted Answer

grep -rin "error: failed to connect" /var/log --include='*.log'. To recursively search only .log files with case-insensitivity and line numbers, use grep with -r, -i, -n, and --include. The --include='*.log' ensures only files with that extension are processed, while -r traverses subdirectories. This combination meets all stated requirements.

Answer

grep -rin "error: failed to connect" /var/log/*.log

Answer

grep -rin "error: failed to connect" /var/log --exclude='*.log'

Answer

grep -rl "error: failed to connect" /var/log

Question 10

An administrator needs to inspect the first few lines of a very large log file /var/log/syslog without loading the entire file into memory, and also needs to follow new entries as they are appended in real time. Which TWO commands or command combinations satisfy these requirements? (Choose two.)

Accepted Answer

head -n 20 /var/log/syslog. Viewing the start of a large file efficiently calls for head, which stops after the requested lines. Following appended entries in real time calls for tail -f, which keeps the file open and prints new data. Commands that scan the entire file, such as cat piped to less, grep over the whole file, or wc, do not meet the efficiency or following requirements.

Answer

wc -l /var/log/syslog

Answer

grep -r '' /var/log/syslog

Answer

cat /var/log/syslog | less

Question 11

An administrator needs to combine two sorted text files, /tmp/a.txt and /tmp/b.txt, into a single sorted stream on standard output while also removing duplicate lines that appear in both files. Which command should be used?

Accepted Answer

sort -u /tmp/a.txt /tmp/b.txt. Sorting both files together with duplicate suppression yields the union of their lines in order, which matches the request. Merge mode preserves duplicates, uniq cannot read two inputs and would clobber the second path, and comm -12 returns only the shared lines, so none of those alternatives produce the required combined, deduplicated stream.

Answer

sort -m /tmp/a.txt /tmp/b.txt

Answer

comm -12 /tmp/a.txt /tmp/b.txt

Answer

uniq /tmp/a.txt /tmp/b.txt

Question 12

A server's root filesystem is filling up. An administrator needs to find the largest regular files under /var, sorted from largest to smallest, while avoiding errors from unreadable directories that are not owned by the administrator. Which command is most appropriate?

Accepted Answer

find /var -type f -printf '%s %p
' 2>/dev/null | sort -rn | head -n 20. The precise approach is to use find restricted to regular files, print size and path, discard error output, then sort numerically in reverse and take the top entries. This avoids directory totals and unreadable-path noise. Recursive ls parsing is unreliable, du shows directory aggregates, and searching only directories answers a different question.

Answer

find /var -type d -exec du -sh {} + | sort -rh

Answer

du -ah /var | sort -rh | head -n 20

Answer

ls -lR /var | sort -k5 -n | tail -n 20

Question 13

A user needs to locate all regular files under /etc that are larger than 1 MB and have not been accessed in the last 30 days. Which command finds these files?

Accepted Answer

find /etc -type f -size +1M -atime +30. The find command is the correct tool for complex file searches based on metadata. The -type f option restricts to regular files, -size +1M selects files larger than 1 MB, and -atime +30 identifies files not accessed in over 30 days. Together, these criteria match the administrator's needs exactly.

Answer

find /etc -type f -size +1M -mtime +30

Answer

locate /etc -type f -size +1M -atime +30

Answer

find /etc -type f -size 1M -atime 30

Question 14

An administrator needs to change the group ownership of the directory /srv/project and all of its existing contents to the group developers, without altering the user ownership. Which command should be used?

Accepted Answer

chgrp -R developers /srv/project. Changing group ownership recursively is the job of chgrp -R. It applies only the group change and leaves user ownership intact, which is precisely what the scenario requires. chown with a bare name targets the user, chmod alters permissions rather than ownership, and usermod operates on account definitions instead of filesystem objects.

Answer

chmod -R g+developers /srv/project

Answer

usermod -g developers /srv/project

Answer

chown -R developers /srv/project

Question 15

A system administrator needs to create a hard link named /home/user/report_hardlink to an existing file /data/reports/report.txt. Which command should be used?

Accepted Answer

ln /data/reports/report.txt /home/user/report_hardlink. The ln command creates hard links by default. Providing the existing file as the first argument and the new link name as the second creates a hard link. Hard links share the same inode and data, so changes to one are reflected in the other. They cannot span filesystems. The correct command simply uses ln with the target and link name.

Answer

ln -s /data/reports/report.txt /home/user/report_hardlink

Answer

ln -h /data/reports/report.txt /home/user/report_hardlink

Answer

link -s /data/reports/report.txt /home/user/report_hardlink