The answer is using the shebang #!/usr/bin/env python3 and validating all external input. The shebang with env improves portability by locating the Python interpreter through the user’s PATH, making the script work across different Linux distributions without hardcoding a specific path like /usr/bin/python3. Validating external input—such as configuration file contents or command-line arguments—prevents injection attacks, a core security principle for any script handling untrusted data. On the CompTIA Linux+ XK0-005 exam, this question tests your understanding of secure scripting practices and environment-agnostic execution, often trapping candidates who choose deprecated options like using backticks for command substitution or relying on relative paths. A common memory tip: think “env for everywhere, validate for safety”—the shebang ensures the script runs on any system, while input validation keeps it secure regardless of the environment.
XK0-005 Scripting, Containers and Automation Practice Question
This XK0-005 practice question tests your understanding of scripting, containers and automation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A Linux administrator writes a Python script to parse configuration files. Which TWO practices improve security and portability? (Select TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Validate all external input before processing
Using #!/usr/bin/env python3 ensures the script uses the correct interpreter from the environment, enhancing portability. Validating all external input prevents injection attacks. The other options are either deprecated or bad practices.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Validate all external input before processing
Why this is correct
Input validation prevents injection attacks and improves security.
Related concept
Authentication checks who the user is.
✗
Use absolute paths for all file operations
Why it's wrong here
Absolute paths reduce portability; relative paths or configuration are better.
✗
Use sudo within the script to run privileged commands
Why it's wrong here
Embedding sudo in a script is a security risk; use proper permissions instead.
✗
Use raw_input() instead of input() in Python 2
Why it's wrong here
raw_input() is Python 2 only; Python 3 uses input() which is safe. This does not apply to modern environments.
✓
Use shebang #!/usr/bin/env python3
Why this is correct
This makes the script portable across systems where python3 may be in different locations.
Related concept
Authentication checks who the user is.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related XK0-005 questions on access control and AAA configuration.
Scripting, Containers and Automation — This question tests Scripting, Containers and Automation — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Validate all external input before processing — Using #!/usr/bin/env python3 ensures the script uses the correct interpreter from the environment, enhancing portability. Validating all external input prevents injection attacks. The other options are either deprecated or bad practices.
What should I do if I get this XK0-005 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related XK0-005 questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
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Question Discussion
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