Quick Answer
The answer is the PATH environment variable. When a script runs manually, your interactive shell provides a fully populated PATH that includes directories like /usr/local/bin and any custom script locations, but cron executes with a severely restricted default PATH—typically just /usr/bin:/bin. If your script calls commands such as mysql, psql, or a custom utility stored outside these two directories, cron will fail with a “command not found” error. On the LPIC-1 exam, this question tests your understanding of the cron environment’s stripped-down nature versus a user’s login shell; it’s a classic trap where candidates assume the script works everywhere because it works in the terminal. The fix is to set the full PATH explicitly inside the script or in the crontab file itself. Memory tip: “Cron cuts corners—PATH is the first place it cuts.”
This LPIC-1 practice question tests your understanding of shells, scripting and data management. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 writes a script that extracts data from a CSV file and inserts it into a database. The script works correctly when run manually but fails when executed by cron. Which environment variable is most likely causing the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
SHELL
Why wrong: SHELL is set by cron to /bin/sh or the user's shell.
LANG
Why wrong: LANG affects locale but not command availability.
HOME
Why wrong: HOME is set by cron to the user's home directory.
PATH
PATH is often not set in cron, causing command not found errors.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
PATH
When a script runs manually, the user's interactive shell inherits a fully populated PATH environment variable that includes directories like /usr/local/bin, /usr/bin, and possibly custom script directories. Cron jobs, however, execute with a minimal environment, and the default PATH for cron is often just /usr/bin:/bin. If the script relies on commands (e.g., mysql, psql, or custom scripts) located outside these directories, cron will fail with a 'command not found' error. Setting the full PATH explicitly inside the script or in the crontab file resolves the issue.
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.
SHELL
Why it's wrong here
SHELL is set by cron to /bin/sh or the user's shell.
LANG
Why it's wrong here
LANG affects locale but not command availability.
HOME
Why it's wrong here
HOME is set by cron to the user's home directory.
PATH
Why this is correct
PATH is often not set in cron, causing command not found errors.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often assume the script's failure is due to a missing HOME or SHELL variable, but the most frequent cron-related issue is the restricted PATH environment, which prevents the script from locating executables.
Trap categories for this question
Command / output trap
LANG affects locale but not command availability.
Detailed technical explanation
Cron's default PATH is set by the cron daemon (often /usr/bin:/bin) and is not inherited from the user's login shell. This is defined in the cron source code or the pam_env configuration. A common real-world scenario is a backup script that calls 'mysqldump' — if /usr/local/mysql/bin is not in cron's PATH, the script fails silently or logs an error. The fix is to either export PATH at the top of the script or use absolute paths for all external commands.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Shells, Scripting and Data Management — study guide chapter
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FAQ
Shells, Scripting and Data Management — This question tests Shells, Scripting and Data Management — Read the scenario before looking for a memorised answer..
The correct answer is: PATH — When a script runs manually, the user's interactive shell inherits a fully populated PATH environment variable that includes directories like /usr/local/bin, /usr/bin, and possibly custom script directories. Cron jobs, however, execute with a minimal environment, and the default PATH for cron is often just /usr/bin:/bin. If the script relies on commands (e.g., mysql, psql, or custom scripts) located outside these directories, cron will fail with a 'command not found' error. Setting the full PATH explicitly inside the script or in the crontab file resolves the issue.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A cron job is configured to run a script every day at 2:30 AM. The sysadmin notices the job runs but produces no output. Which is the most likely reason?
easyWhy C: Option C is correct because cron jobs run in a non-interactive, non-terminal environment. By default, cron captures any output (stdout/stderr) from the job and attempts to email it to the user. If the MAILTO variable is not set and the output is not redirected to a file or /dev/null, the output is simply discarded, resulting in no visible output. The job still runs successfully, but the output is lost.
Variation 2. Refer to the exhibit. Why does the cron job fail?
hardWhy C: C is correct because cron jobs require the script to be executable (i.e., have the execute permission bit set). If the script is not executable, cron will fail to run it even if the shebang line and PATH are correct. The error typically appears in the cron log or as a silent failure.
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Last reviewed: Jun 11, 2026
This LPIC-1 practice question is part of Courseiva's free LPI 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 LPIC-1 exam.
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