Type the special parameter, including its leading dollar sign, that expands to the exit status of the most recently completed foreground command.
LPIC-1 Exam 102-500, objective 105. Shells and shell scripting easy
Machine-checked — no person has signed for it. This question was read against the source cited below by an automated pass, which found no contradiction. That is a weaker claim than it sounds: the same kind of process wrote the question, so it can confirm its own mistake.
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How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
Answer
Type the answer.
Accepted answer
$?
Case sensitive — Linux is, and grading LS as ls would teach a falsehood.
Why
$? holds the exit status of the last foreground command: 0 for success, non-zero for failure. It is overwritten by the very next command, including by an `echo`, so capture it at once with something like `status=$?` if you need it twice. Related parameters: $$ is the shell's own PID, $! the PID of the last background job, $0 the name the script was invoked as, and $# the number of positional parameters.
Where this comes from
- Cited
- LPI exam objective 105.2
- What it says
- Read the exit status of the previous command.
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 105 and space the ones you get wrong.
More questions on this objective
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