UNIX ADMINISTRATOR CERTIFICATION –QUESTIONS AND CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF.
SECTION ONE: QUESTIONS 1–100
1. Which command is used to display the current directory's disk usage in a human-readable format?
A. du -h
B. df -k
C. ls -l
D. stat -r
🟢A
🔴 RATIONALE: The du (disk usage) command with the -h flag provides disk usage estimates in
human-readable units like KB, MB, or GB.
2. Which signal is sent to a process when the 'kill' command is executed without any specific flags?
A. SIGINT
B. SIGTERM
C. SIGKILL
D. SIGHUP
🟢B
🔴 RATIONALE: By default, the kill command sends SIGTERM (15), which allows the process to
perform cleanup tasks before exiting.
3. You need to ensure that a shell script remains running even after the user logs out. Which
command is best suited for this?
A. bg
B. nohup
C. disown
D. watch
, 🟢B
🔴 RATIONALE: The nohup command ignores the SIGHUP signal, preventing the process from
terminating when the terminal session ends.
4. Which file contains the user account information, including the user ID, group ID, and home
directory?
A. /etc/shadow
B. /etc/group
C. /etc/passwd
D. /etc/profile
🟢C
🔴 RATIONALE: The /etc/passwd file stores essential user account information. /etc/shadow stores
encrypted passwords.
5. What is the primary purpose of the 'umask' setting?
A. To define the default shell environment
B. To set default file permissions for new files
C. To restrict user access to specific directories
D. To encrypt file names upon creation
🟢B
🔴 RATIONALE: The umask (user file-creation mask) determines the default permissions for files
and directories created by a user.
6. Which command effectively changes the owner of a file to user 'admin'?
A. chmod admin filename
B. chgrp admin filename
C. chown admin filename
, D. chown -u admin filename
🟢C
🔴 RATIONALE: The chown command is used to change the owner of a file or directory.
7. In the context of ethical standards, which action is most appropriate when discovering an
unpatched vulnerability on a production server?
A. Immediately exploit it to prove existence
B. Report it through the established incident response channel
C. Ignore it as long as the system is stable
D. Post the details on a public forum
🟢B
🔴 RATIONALE: Professional ethics dictate that security vulnerabilities must be reported through
proper organizational channels to minimize risk and ensure remediation.
8. Which directory contains system-wide configuration files?
A. /bin
B. /etc
C. /var
D. /opt
🟢B
🔴 RATIONALE: The /etc directory is the standard location for system-wide configuration files in
Unix-like operating systems.
9. What does the command 'ls -la' display?
A. Files including hidden ones, in long format
B. Files by size, in ascending order
C. Hidden files only
, D. Directories only, sorted alphabetically
🟢A
🔴 RATIONALE: The -l option provides long format listing, and -a ensures all files, including hidden
ones (starting with a dot), are shown.
10. Which utility is used to monitor real-time system performance and process activity?
A. ps
B. top
C. nice
D. vmstat
🟢B
🔴 RATIONALE: The top command provides a dynamic, real-time view of running system
processes and resource utilization.
11. What is the purpose of the sticky bit on a directory?
A. To make the directory read-only
B. To prevent users from deleting files owned by others
C. To ensure the directory is always backed up
D. To allow recursive execution of scripts
🟢B
🔴 RATIONALE: When the sticky bit is set on a directory, only the file owner, directory owner, or
root can delete or rename files within that directory.
12. Which shell environment variable holds the list of directories to search for executable commands?
A. PATH
B. SHELL
C. HOME
ANSWERS) PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF.
SECTION ONE: QUESTIONS 1–100
1. Which command is used to display the current directory's disk usage in a human-readable format?
A. du -h
B. df -k
C. ls -l
D. stat -r
🟢A
🔴 RATIONALE: The du (disk usage) command with the -h flag provides disk usage estimates in
human-readable units like KB, MB, or GB.
2. Which signal is sent to a process when the 'kill' command is executed without any specific flags?
A. SIGINT
B. SIGTERM
C. SIGKILL
D. SIGHUP
🟢B
🔴 RATIONALE: By default, the kill command sends SIGTERM (15), which allows the process to
perform cleanup tasks before exiting.
3. You need to ensure that a shell script remains running even after the user logs out. Which
command is best suited for this?
A. bg
B. nohup
C. disown
D. watch
, 🟢B
🔴 RATIONALE: The nohup command ignores the SIGHUP signal, preventing the process from
terminating when the terminal session ends.
4. Which file contains the user account information, including the user ID, group ID, and home
directory?
A. /etc/shadow
B. /etc/group
C. /etc/passwd
D. /etc/profile
🟢C
🔴 RATIONALE: The /etc/passwd file stores essential user account information. /etc/shadow stores
encrypted passwords.
5. What is the primary purpose of the 'umask' setting?
A. To define the default shell environment
B. To set default file permissions for new files
C. To restrict user access to specific directories
D. To encrypt file names upon creation
🟢B
🔴 RATIONALE: The umask (user file-creation mask) determines the default permissions for files
and directories created by a user.
6. Which command effectively changes the owner of a file to user 'admin'?
A. chmod admin filename
B. chgrp admin filename
C. chown admin filename
, D. chown -u admin filename
🟢C
🔴 RATIONALE: The chown command is used to change the owner of a file or directory.
7. In the context of ethical standards, which action is most appropriate when discovering an
unpatched vulnerability on a production server?
A. Immediately exploit it to prove existence
B. Report it through the established incident response channel
C. Ignore it as long as the system is stable
D. Post the details on a public forum
🟢B
🔴 RATIONALE: Professional ethics dictate that security vulnerabilities must be reported through
proper organizational channels to minimize risk and ensure remediation.
8. Which directory contains system-wide configuration files?
A. /bin
B. /etc
C. /var
D. /opt
🟢B
🔴 RATIONALE: The /etc directory is the standard location for system-wide configuration files in
Unix-like operating systems.
9. What does the command 'ls -la' display?
A. Files including hidden ones, in long format
B. Files by size, in ascending order
C. Hidden files only
, D. Directories only, sorted alphabetically
🟢A
🔴 RATIONALE: The -l option provides long format listing, and -a ensures all files, including hidden
ones (starting with a dot), are shown.
10. Which utility is used to monitor real-time system performance and process activity?
A. ps
B. top
C. nice
D. vmstat
🟢B
🔴 RATIONALE: The top command provides a dynamic, real-time view of running system
processes and resource utilization.
11. What is the purpose of the sticky bit on a directory?
A. To make the directory read-only
B. To prevent users from deleting files owned by others
C. To ensure the directory is always backed up
D. To allow recursive execution of scripts
🟢B
🔴 RATIONALE: When the sticky bit is set on a directory, only the file owner, directory owner, or
root can delete or rename files within that directory.
12. Which shell environment variable holds the list of directories to search for executable commands?
A. PATH
B. SHELL
C. HOME
