LFCS Essential Commands Practice Test 7 — 15 Questions

Question 1

An administrator needs to compress a directory named 'project' into a tarball with maximum compression using gzip. Which command is appropriate?

Accepted Answer

tar -czvf archive.tar.gz project. The `-z` flag tells tar to compress the archive using gzip. The `-c` flag creates a new archive, `-v` provides verbose output, and `-f` specifies the archive filename. The `.tar.gz` extension is the conventional extension for a gzip-compressed tarball. Although other tools like bzip2 or xz can achieve higher compression ratios, the question explicitly asks for using gzip.

Answer

tar -cjvf archive.tar.bz2 project

Answer

tar -cJvf archive.tar.xz project

Answer

tar -cvf archive.tar project

Question 2

A junior admin runs 'ls -l' and sees permissions '-rwxrwxr-x' on a file. What is the octal representation?

Accepted Answer

775. The permissions '-rwxrwxr-x' break down as: owner (rwx = 4+2+1 = 7), group (rwx = 4+2+1 = 7), others (r-x = 4+0+1 = 5). This gives the octal value 775. Option C is correct because it matches this calculation exactly.

Answer

755

Answer

770

Answer

777

Question 3

A system administrator wants to kill a process with PID 1234 that is not responding to SIGTERM. Which command will forcefully terminate it?

Accepted Answer

kill -9 1234. Kill -9 (SIGKILL) sends signal 9, which cannot be caught, blocked, or ignored by the process. Unlike SIGTERM (signal 15), SIGKILL forces the kernel to immediately terminate the process without allowing it to clean up, making it the appropriate choice when a process is unresponsive to SIGTERM.

Answer

kill -1 1234

Answer

kill -15 1234

Answer

kill -SIGTERM 1234

Question 4

A user needs to see the contents of a gzip-compressed file 'data.txt.gz' without decompressing it. Which command is appropriate?

Accepted Answer

zcat data.txt.gz. The `zcat` command reads a gzip-compressed file and outputs its decompressed content to stdout without modifying the original file. This allows the user to view the contents of 'data.txt.gz' without permanently decompressing it.

Answer

gunzip data.txt.gz

Answer

./data.txt.gz

Answer

gzcat data.txt.gz

Question 5

An administrator wants to print the last field of each line from a CSV file 'data.csv' (comma-separated). Which awk command accomplishes this?

Accepted Answer

awk -F, '{print $NF}' data.csv. `awk -F, '{print $NF}' data.csv` uses `-F,` to set the field separator to comma, and `$NF` represents the value of the last field (NF is the number of fields, so $NF is the last field). This command prints the last column of each line in the CSV file.

Answer

cut -d, -f2 data.csv

Answer

cut -d, -f1 data.csv

Answer

awk '{print $NF}' data.csv

Question 6

A user 'dba' tries to login via SSH and fails. Based on the exhibit, what is the most likely cause?

Accepted Answer

The user 'dba' has an invalid login shell.. The exhibit shows that the user 'dba' has an invalid login shell (e.g., /sbin/nologin or /bin/false). When the login shell is set to a non-interactive shell, SSH authentication succeeds but the session immediately closes, preventing the user from logging in. This is a common configuration for system accounts or users who should not have interactive shell access.

Answer

The file /home/dba/file.txt is corrupt.

Answer

The user 'dba' is not in the 'docker' group.

Answer

The home directory /home/dba does not have correct permissions.

Question 7

Which TWO commands can be used to display the contents of a text file page by page? (Select two.)

Accepted Answer

more file.txt. Option C, more file.txt, is correct because more is a pager that displays a text file one screenful at a time, pausing at each page until the user presses Space or Enter to continue. Option D, less file.txt, is also correct because less is a more advanced pager that likewise presents file contents page by page, while additionally allowing backward scrolling and searching. Both commands satisfy the requirement of paging through a file's contents rather than dumping them all at once. In contrast, A (cat file.txt) writes the entire file to standard output in one continuous stream, B (head file.txt) shows only the first 10 lines by default, and E (tail file.txt) shows only the last 10 lines by default, so none of these paginate the output.

Answer

cat file.txt

Answer

head file.txt

Answer

tail file.txt

Question 8

A user reports that they cannot run a script because it says 'Permission denied'. The script is owned by root and has permissions -rw-r--r--. Which command would allow the user to execute the script?

Accepted Answer

chmod +x script. The script has permissions `-rw-r--r--`, meaning the owner (root) has read/write, but no execute bit is set for any user. Option B (`chmod +x script`) adds the execute permission for all users (owner, group, others), which allows the user to run the script. Without the execute bit, the kernel will refuse to execve() the file, returning EACCES.

Answer

chmod u+s script

Answer

chmod -w script

Answer

chown user:user script

Question 9

A system administrator has a cron job that runs a backup script. The script requires the variable BACKUP_DIR to be set, but the administrator cannot modify the script. Which is the most appropriate place to define the variable for cron?

Accepted Answer

In the crontab file with the line 'BACKUP_DIR=/var/backups' before the command. Cron jobs run in a minimal environment and do not source shell profiles or login scripts. Defining BACKUP_DIR directly in the crontab file before the command ensures the variable is set in the cron execution context, which is the only reliable way to pass environment variables to cron without modifying the script.

Answer

In /etc/profile.d/backup.sh

Answer

In /etc/environment

Answer

In ~/.bash_profile

Question 10

An administrator needs to replace all occurrences of the string 'foo' with 'bar' in all files under /etc/config, but only in files ending with .conf. The replacement must be done in-place, and backup copies should be created with a .bak extension. Which command accomplishes this?

Accepted Answer

find /etc/config -name '*.conf' -exec sed -i.bak 's/foo/bar/g' {} +. It uses `sed -i.bak` which creates a backup file with the .bak extension before performing the in-place substitution, and the `find -exec ... +` variant efficiently processes multiple files at once. The `-i` option with an argument (no space) specifies the backup suffix directly, satisfying the requirement for backup copies.

Answer

find /etc/config -name '*.conf' -exec sed -i .bak 's/foo/bar/g' {} +

Answer

find /etc/config -name '*.conf' -exec sed 's/foo/bar/g' {} \;

Answer

find /etc/config -name '*.conf' -exec sed -i 's/foo/bar/g' {} +

Question 11

A user wants to view the contents of a compressed log file /var/log/syslog.2.gz without decompressing it first. Which command should they use?

Accepted Answer

zcat /var/log/syslog.2.gz. `zcat` is a utility that reads compressed files (typically gzip-compressed) and outputs their decompressed content to standard output without permanently decompressing the file. This allows the user to view the contents of `/var/log/syslog.2.gz` directly in the terminal.

Answer

gunzip /var/log/syslog.2.gz

Answer

cat /var/log/syslog.2.gz

Answer

less /var/log/syslog.2.gz

Question 12

Which command displays the amount of free and used memory in the system?

Accepted Answer

free -h. The `free -h` command displays the total, used, and free physical memory (RAM) and swap space in a human-readable format (e.g., GiB, MiB). The `-h` flag converts raw byte counts into appropriate units, making it the correct tool for checking memory usage.

Answer

df -h

Answer

ps aux

Answer

netstat -i

Question 13

Which TWO commands can be used to view the last 10 lines of a file and also follow new lines as they are written?

Accepted Answer

tail -f -n 10. Option A, `tail -f -n 10`, is correct because `-n 10` displays the last 10 lines of the file and `-f` (follow) keeps the file open and prints new lines as they are appended, which is exactly the requested behavior. Option E, `less +F`, is correct because the `+F` command starts `less` in follow mode, initially showing the file content (including the tail end) and continuously displaying newly appended lines, similar to `tail -f`. Option B, `cat -n`, only concatenates the file with line numbers and does not follow new lines. Option C, `tail -n 10`, shows the last 10 lines but lacks the follow capability. Option D, `head -n 10`, shows the first 10 lines and does not follow the file.

Answer

cat -n

Answer

tail -n 10

Answer

head -n 10

Question 14

Which THREE of the following commands can be used to search for a string in multiple files and display the matching lines?

Accepted Answer

ack 'pattern' /path. Option B, ack 'pattern' /path, is correct because ack is a recursive grep-like search tool that by default searches files under the given path and prints matching lines with filenames. Option C, grep -r 'pattern' /path, is correct because the -r (recursive) flag makes grep descend into directories and display each matching line prefixed by its file. Option D, rg 'pattern' /path, is correct because ripgrep recursively searches the path and outputs matching lines, honoring ignore files by default. Option A, find /path -name '*.txt' -type f, only locates files by name and type; it does not search file contents or display matching lines. Option E, sort /path/file, merely sorts lines of a single file and performs no pattern search.

Answer

find /path -name '*.txt' -type f

Answer

sort /path/file

Question 15

Which TWO commands can be used to display the current working directory?

Accepted Answer

pwd. Option B, `pwd`, is correct because it is the dedicated shell builtin/utility that prints the absolute pathname of the current working directory. Option D, `echo $PWD`, is correct because the shell maintains the `PWD` environment variable holding the current working directory, and `echo` expands it to display that path. Option A, `which pwd`, only locates the executable or builtin for `pwd` and prints its path rather than the working directory. Option C, `date`, displays the current system date and time, and option E, `whoami`, prints the effective username — neither relates to the working directory.

Answer

which pwd

Answer

date

Answer

whoami