Quick Answer
The answer is `ls -lart`. This command works because `ls -l` produces a long listing format, `-a` includes all files including hidden files (those starting with a dot), `-t` sorts entries by modification time with the newest first, and `-r` reverses that order so the oldest files appear first. On the Linux Foundation Certified System Administrator LFCS exam, this question tests your ability to combine flags efficiently rather than using a longer pipeline like `ls -la | sort -k6,7`; a common trap is forgetting the `-r` flag, which would list newest files first instead of oldest. The search intent "list all files including hidden sorted by modification time oldest first" is exactly what `ls -lart` accomplishes in a single, memorable command. For a quick memory tip, think of the mnemonic "LART" — Long listing, All files, Reverse time — and remember that reversing the default newest-first sort gives you the oldest first.
This LFCS practice question tests your understanding of essential commands. 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.
A system administrator needs to list all files in the current directory, including hidden files, in a long listing format sorted by modification time (oldest first). Which command achieves this?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
ls -lihrt
Why wrong: Includes inode and human-readable but missing -t, sorts by name.
ls -lart
Correct: long, all, reverse, time.
ls -lat
Why wrong: Shows newest first, not oldest.
ls -lrt
Why wrong: Lacks -a, so hidden files not shown.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
ls -lart
Option B is correct because `ls -lart` combines the `-l` (long listing), `-a` (include hidden files starting with dot), `-r` (reverse order), and `-t` (sort by modification time, newest first). The reverse flag flips the sort to oldest first, meeting the requirement exactly.
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.
ls -lihrt
Why it's wrong here
Includes inode and human-readable but missing -t, sorts by name.
ls -lart
Why this is correct
Correct: long, all, reverse, time.
Clue confirmation
The clue words "first", "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
ls -lat
Why it's wrong here
Shows newest first, not oldest.
ls -lrt
Why it's wrong here
Lacks -a, so hidden files not shown.
Common exam traps
The trap here is that candidates often remember `-lt` for time-sorted listing but forget that `-a` is required to include hidden files, or they confuse the order and omit `-r` to reverse to oldest first.
Trap categories for this question
Command / output trap
Shows newest first, not oldest.
Detailed technical explanation
The `ls` command uses the `stat` system call to retrieve file timestamps (mtime, atime, ctime). The `-t` flag sorts by `st_mtime` (modification time) in descending order; `-r` reverses that order. Hidden files are those whose names begin with a dot (`.`), and `-a` forces `ls` to include directory entries `.` and `..` as well. In scripting, omitting `-a` can lead to missed configuration files like `.bashrc` or `.gitignore`.
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 LFCS 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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Essential Commands — This question tests Essential Commands — Read the scenario before looking for a memorised answer..
The correct answer is: ls -lart — Option B is correct because `ls -lart` combines the `-l` (long listing), `-a` (include hidden files starting with dot), `-r` (reverse order), and `-t` (sort by modification time, newest first). The reverse flag flips the sort to oldest first, meeting the requirement exactly.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "first", "which command". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This LFCS practice question is part of Courseiva's free Linux Foundation 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 LFCS exam.
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