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XK0-006 Practice Question: A Linux system administrator for a small company

You are a Linux system administrator for a small company. You have written a BASH script that checks disk usage and sends an email alert if any partition exceeds 90% usage. The script works when run manually but does not produce alerts when run via cron. Which of the following is the most likely cause?

⚠ Common exam trap

CompTIA often tests the concept that cron jobs have a restricted environment, particularly PATH, and candidates mistakenly focus on script permissions or relative paths instead of the missing command path in cron's minimal shell.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The cron job's PATH variable does not include the directory where the mail command is located

When a script runs manually, it inherits the user's interactive shell environment, including the PATH variable that typically includes directories like /usr/bin and /usr/local/bin where the mail command resides. However, cron jobs execute in a minimal environment with a very restricted PATH (often just /usr/bin:/bin). If the mail command is located in a directory not in cron's default PATH, such as /usr/sbin or /opt/bin, the script will fail silently when attempting to send the email, even though the disk usage check itself succeeds. This is the most common cause of scripts working manually but failing under cron.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • ✓

    The cron job's PATH variable does not include the directory where the mail command is located

    Why this is correct

    Cron runs with a minimal environment, so its PATH typically omits /usr/bin or /bin where mail resides. The script's manual success relies on your interactive PATH. Specifying the absolute path to mail, or exporting PATH within the script, resolves the missing-command failure.

  • ✗

    The script has incorrect file permissions

    Why it's wrong here

    Permissions cannot be the cause: the script runs successfully from the shell, proving execute and read bits are already sufficient. It tempts because permission errors are a common cron failure, and would be correct if cron logged a permission-denied error instead of running the script.

  • ✗

    The cron scheduler is disabled

    Why it's wrong here

    Cron itself clearly runs, since the script executes but produces no alert; a disabled daemon would suppress all scheduled jobs, not just this one. It tempts because a stopped crond is a genuine cause of silent cron failures, and would be correct if no jobs ran at all.

  • ✗

    The script uses relative paths to check partitions

    Why it's wrong here

    Relative paths would break manual execution too, since the shell's working directory differs from cron's; the script works by hand, so paths resolve. It tempts because cron's minimal environment genuinely breaks relative paths, and would be correct if the script failed in both contexts.

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JA

Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

This XK0-006 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the XK0-006 exam.