LX0-104 · Question #153
In the following output, what does the 1 in the b column indicate?
The correct answer is D. A process is blocked on I/O.. In common Unix-like system monitoring tools, a 'b' column often represents a blocked state, where '1' indicates a process is blocked, typically on I/O.
Question
Options
- AA process is swapped and waiting.
- BA process is waiting.
- CA process is waiting on a parent to check its exit value.
- DA process is blocked on I/O.
How the community answered
(41 responses)- A5% (2)
- C2% (1)
- D93% (38)
Why each option
In common Unix-like system monitoring tools, a 'b' column often represents a blocked state, where '1' indicates a process is blocked, typically on I/O.
While a process might be swapped, the 'b' column specifically indicates blocking, not a combination of swapped and waiting.
'Waiting' is too general; the 'b' column specifically implies a blocked state, often on I/O, rather than just any waiting condition.
A process waiting on a parent to check its exit value is a 'zombie' state, typically indicated by 'Z' in process status, not 'b'.
In tools like `vmstat` or certain `ps` outputs on Linux, the 'b' column (often under 'w' or 'wait') signifies the number of processes currently blocked, most commonly waiting for I/O operations to complete. A '1' in this column means one process is in this I/O wait state.
Concept tested: Linux process blocked state
Source: https://man7.org/linux/man-pages/man1/vmstat.1.html
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