A colleague added a kernel argument at the boot loader menu and you want to confirm that the running kernel actually received it. Type the full path of the virtual file that shows the command line the running kernel was started with.
LPIC-1 Exam 101-500, objective 101. System architecture medium
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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Answer
Type the answer.
Accepted answer
/proc/cmdline
Case sensitive — Linux is, and grading LS as ls would teach a falsehood.
Why
The boot loader passes a single command-line string to the kernel, and the kernel exposes exactly that string, verbatim, as /proc/cmdline for the life of the boot. It is the authoritative answer to what the kernel was told, whereas the boot loader configuration only says what it would be told at the next boot. Arguments the kernel does not recognise are not errors: those in key=value form are passed on to PID 1 as environment variables and the rest as its arguments, and PID 1 may also read the string for itself, which is how systemd picks up parameters such as systemd.unit=.
Where this comes from
- Cited
- manual page proc(5)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 101 and space the ones you get wrong.
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