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Question

Difficulty: HardmacOS and Linux Operating System Features and Tools

A Linux system administrator is troubleshooting a non-responsive background application process named `data_sync` with process ID (PID) 5412. The administrator previously attempted to stop the process using the standard `kill 5412` command, but the process continues to run and consume system resources. Which command should the administrator execute to force the immediate termination of the process by sending a non-catchable signal?

  1. kill -9 5412Answer
  2. B
    kill -15 5412
  3. C
    pkill -stop 5412
  4. D
    chmod 000 5412

Answer

The command `kill -9 5412` is correct because signal 9 (SIGKILL) forces immediate process termination by the operating system kernel, overriding hung or non-responsive application states.
The correct option `kill -9 5412` issues SIGKILL directly to the specified PID. SIGKILL cannot be blocked, caught, or ignored by an application, making it the required choice to forcibly stop frozen processes.

Step-by-Step Solution

1
Identify the state of the target process and why the previous signal failed.
The standard `kill PID` command transmits signal 15 (SIGTERM), allowing the target process to handle cleanup before exiting. If a process is hung or non-responsive, it may fail to handle SIGTERM.
Understanding signal handling explains why default termination commands fail on frozen processes.
2
Select the appropriate signal to force process termination.
Signal 9 (SIGKILL) instructs the Linux kernel to immediately release the memory and terminate the process without waiting for the process to intercept the signal.
SIGKILL is mandatory when a process ignores SIGTERM.
3
Construct the exact command syntax using the target process ID.
Execute `kill -9 5412` to terminate PID 5412.
Combining the `kill` utility with flag `-9` and the explicit numeric PID achieves immediate, forced termination.

Key Concept

Linux/macOS process control signals (SIGTERM vs SIGKILL)
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Topics

macOS and Linux Operating System Features and Tools

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