In UNIX 'du' usage, which option displays the number of blocks used by a file (summarized usage)?

Introduction / Context:
The du (disk usage) command reports filesystem usage in blocks or human-readable units. Choosing the correct option lets administrators quickly summarize consumption by a file or directory, which is crucial for quota checks and cleanup tasks on multi-user systems.

Given Data / Assumptions:

• We are referring to standard du behavior (POSIX-like).
• Goal: summarize the number of blocks used (not a recursive detailed list).
• Options presented mimic common du switches.

Concept / Approach:

du -s prints a summary for each argument—effectively the total blocks used by that file or directory, instead of listing every subentry. Other switches: -c adds a grand total line, -i (on some platforms) reports inode usage, and -d limits depth (GNU extension), but none replace the summary role of -s.

Step-by-Step Solution:

Verification / Alternative check:

Example: du -s /var/log outputs a single number and path, representing total blocks used by /var/log, confirming the summary behavior.

Why Other Options Are Wrong:

• -c: adds cumulative total but still lists entries unless combined with -s.
• -i: inode counts, not blocks.
• -d: depth limit; not a summary by itself.
• None of the above: incorrect because -s is correct.

Common Pitfalls:

• Confusing du with ls -s, which shows per-file block sizes.
• Forgetting human-readable option (-h) for MB/GB formatting when needed.

Final Answer:

-s.