This EX200 practice question tests your understanding of essential tools. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which THREE file descriptors are always available for every Unix process?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "always"
Why it matters: Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
4: socket
Why wrong: Not automatically open.
3: log file
Why wrong: Not automatically open.
2: stderr
Always open for error output.
1: stdout
Always open for output.
0: stdin
Always open for input.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
2: stderr
Option C is correct because file descriptor 2 (stderr) is one of the three standard file descriptors that every Unix process inherits from its parent process. These descriptors are opened automatically by the kernel when a process starts, providing default channels for input (stdin, fd 0), output (stdout, fd 1), and error output (stderr, fd 2).
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
4: socket
Why it's wrong here
Not automatically open.
3: log file
Why it's wrong here
Not automatically open.
2: stderr
Why this is correct
Always open for error output.
Clue confirmation
The clue word "always" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
1: stdout
Why this is correct
Always open for output.
Clue confirmation
The clue word "always" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
0: stdin
Why this is correct
Always open for input.
Clue confirmation
The clue word "always" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Red Hat often tests the misconception that file descriptors beyond 0, 1, and 2 are standard or always available, leading candidates to select options like '3: log file' or '4: socket' as if they were universally present.
Detailed technical explanation
Under the hood, the kernel allocates file descriptors from a per-process file descriptor table, with slots 0, 1, and 2 pre-populated by the fork/exec sequence. In a real-world scenario, if a daemon closes all inherited file descriptors for security, it must explicitly reopen stdin, stdout, and stderr (often to /dev/null) to maintain standard I/O behavior, or risk unexpected failures when writing error messages.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the EX200 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Essential Tools — This question tests Essential Tools — Read the scenario before looking for a memorised answer..
The correct answer is: 2: stderr — Option C is correct because file descriptor 2 (stderr) is one of the three standard file descriptors that every Unix process inherits from its parent process. These descriptors are opened automatically by the kernel when a process starts, providing default channels for input (stdin, fd 0), output (stdout, fd 1), and error output (stderr, fd 2).
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "always". Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This EX200 practice question is part of Courseiva's free Red Hat 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 EX200 exam.
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