LFCS Practice Test 22 — 15 Questions

Question 1

What is the purpose of the chmod 755 command in this exhibit?

Accepted Answer

Set permissions to rwxr-xr-x. The chmod 755 command sets the file permissions to rwxr-xr-x, meaning the owner has read, write, and execute permissions (7), while the group and others have read and execute permissions (5). This is a common permission set for executable scripts and directories to allow execution without granting write access to non-owners.

Answer

Add execute permission for the owner only

Answer

Remove write permission for others

Answer

Set the setuid bit

Question 2

An administrator is troubleshooting intermittent connectivity issues. Running 'ping -c 100 -i 0.2 10.0.0.1' shows about 5% packet loss. What is the primary purpose of the '-i 0.2' option?

Accepted Answer

It sets the interval between pings to 0.2 seconds. The '-i 0.2' option in the ping command sets the interval between sending ICMP Echo Request packets to 0.2 seconds. This allows the administrator to send pings more frequently than the default (typically 1 second), which helps in detecting intermittent connectivity issues over a shorter test duration. By sending 100 packets at a 0.2-second interval, the test completes in about 20 seconds, making it practical for troubleshooting transient packet loss.

Answer

It sets the TTL to 0.2

Answer

It sets the timeout to 0.2 seconds

Answer

It sets the packet size to 0.2 bytes

Question 3

A company follows the principle of least privilege. Several developers need sudo access to run specific commands like systemctl and journalctl. What is the best practice for granting this access?

Accepted Answer

Create a new group 'devops', add developers to it, and create a sudoers drop-in file with rules for specific commands. It follows the principle of least privilege by creating a dedicated 'devops' group and using a sudoers drop-in file (e.g., /etc/sudoers.d/devops) to grant only specific commands like systemctl and journalctl. This avoids modifying the main /etc/sudoers file directly, which is error-prone, and ensures that developers have no more privileges than necessary. The drop-in file approach is the recommended best practice for maintainability and security.

Answer

Use 'usermod -a -G sudo' for each developer and edit /etc/sudoers manually with visudo

Answer

Add all developers to the 'wheel' group and configure %wheel ALL=(ALL) ALL

Answer

Edit /etc/sudoers directly to add each developer username with command restrictions

Question 4

Which TWO commands can display the current environment variables?

Accepted Answer

env. The `env` command (option C) is correct because it prints all current environment variables and their values to standard output when run without arguments. The `printenv` command (option E) is also correct because it displays the values of all environment variables (or a specified one) in the current shell environment. Option A, `set`, is not marked correct because although it lists shell variables, it also includes shell functions and local variables, not strictly the environment variables. Option B, `echo $HOME`, is not marked correct because it only displays the value of the single HOME variable rather than the current environment variables as a whole. Option D, `export`, is not marked correct because it is used to mark variables for export to child processes, not to display the environment.

Answer

set

Answer

echo $HOME

Answer

export

Question 5

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 6

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 7

A system administrator wants to display a list of all currently running processes with their parent process IDs. Which command is most appropriate?

Accepted Answer

ps -ef. (ps -ef) is correct because the 'ps' command with the '-e' flag displays all processes, and the '-f' flag provides a full-format listing that includes the PPID (parent process ID) in the output. This directly meets the requirement to list all currently running processes with their parent process IDs.

Answer

pstree

Answer

jobs

Answer

top

Question 8

An administrator wants to change the primary group of user 'jane' from 'staff' to 'developers'. Which command accomplishes this?

Accepted Answer

usermod -g developers jane. The `usermod -g` command changes the primary group of a user. The `-g` option specifies the new primary group (by name or GID), and the user's existing primary group is replaced. This directly accomplishes the administrator's goal of changing jane's primary group from 'staff' to 'developers'.

Answer

usermod -G developers jane

Answer

groupmod -g developers jane

Answer

chgrp developers jane

Question 9

A developer wants to change the ownership of a directory and all its contents recursively to user 'appuser' and group 'appgroup'. Which command accomplishes this?

Accepted Answer

chown -R appuser:appgroup /app. The `chown -R appuser:appgroup /app` command recursively changes both the user and group ownership of the `/app` directory and all its contents. The `-R` flag ensures recursion, and the colon-separated `user:group` syntax sets both ownership attributes in a single command.

Answer

chown -R appuser /app && chgrp appgroup /app

Answer

chgrp -R appgroup /app && chown appuser /app

Answer

chown -R appuser: /app && chgrp -R appgroup /app

Question 10

Which command will display all groups a specific user belongs to, including both primary and supplementary groups?

Accepted Answer

groups username. The 'groups' command is the standard utility to list all group memberships for a given user, showing both the primary group (from /etc/passwd) and any supplementary groups (from /etc/group). It queries the system's group database directly, making it the correct and simplest choice for this task.

Answer

cat /etc/passwd | grep username

Answer

id -g username

Answer

grep username /etc/group

Question 11

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 12

To check the disk usage of the /var/log directory in a human-readable format, which command is appropriate?

Accepted Answer

du -sh /var/log. The `du -sh /var/log` command is correct because `du` (disk usage) estimates file and directory space usage, and the `-s` option summarizes the total for the specified directory, while `-h` prints sizes in human-readable format (e.g., K, M, G). This directly answers the requirement to check disk usage of the /var/log directory in a human-readable form.

Answer

ls -lh /var/log

Answer

df -h /var/log

Answer

fdisk -l /var/log

Question 13

An administrator runs 'ls -la' and sees the following entry for a file: 'lrwxrwxrwx 1 root root 24 Jan 10 12:00 link -> /etc/passwd'. If the target file /etc/passwd is deleted, what happens to the link file?

Accepted Answer

The link becomes a broken symbolic link. The entry 'lrwxrwxrwx' indicates a symbolic link (symlink), which stores a path to the target file rather than sharing its inode. When the target /etc/passwd is deleted, the symlink still exists but points to a non-existent path, making it a broken (dangling) symlink. Accessing it will result in a 'No such file or directory' error.

Answer

The link becomes a hard link to the deleted file's inode

Answer

The link becomes a regular file with the same content

Answer

The link is automatically deleted

Question 14

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 15

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