System administration: Which command cleanly halts (powers down) a Linux system by changing runlevel to 0?

Introduction / Context:
Shutting down a Linux system safely ensures filesystems are synced and services are stopped in order. There are several commands and key sequences, but one classic method is to request runlevel 0 (halt) through init/systemd compatibility.

Given Data / Assumptions:

• Legacy SysV-style runlevels: 0 = halt/poweroff, 6 = reboot.
• We want a clean halt sequence, not just a reboot or terminal key combo.
• Modern systems may use systemctl poweroff, but init 0 remains widely recognized.

Concept / Approach:
init 0 transitions the system to runlevel 0, triggering shutdown scripts to stop services, unmount filesystems, and power off. It is safe and orderly. Other syntaxes like shutdown -h now achieve the same end; the distractor options here are incorrect or non-Linux specific.

Step-by-Step Solution:

Verification / Alternative check:
Observe console messages indicating services stopping and filesystems unmounted. After completion, hardware powers down or halts at a safe state.

Why Other Options Are Wrong:
shutdown -t: Incomplete/incorrect syntax; -t typically specifies a timeout, not a full command. shutdown -g -y0: A Solaris-style syntax, not Linux standard. Ctrl+Alt+Del: Usually triggers reboot, not halt. None of the above: Incorrect because init 0 is valid.

Common Pitfalls:
Forgetting required privileges; abruptly powering off without shutdown risks data loss; confusing halt vs reboot runlevels.

Final Answer:
init 0