The top command provides a dynamic, real-time view of a running system. Its output is divided into two main sections. The top summary area displays system-wide statistics, including overall CPU utilization (e.g., %us, %sy, %id) and memory usage (total, free, used). The lower section lists the currently running processes, ordered by resource consumption, showing individual process details like Process ID (PID), user, and specific CPU and memory percentage utilization. This single utility comprehensively fulfills all requirements of the question.

A. df: This command reports file system disk space usage and available space, not CPU, memory, or process resource consumption.

B. free: This command displays the total, used, and free amounts of physical and swap memory but does not provide CPU or per-process utilization details.

C. ps: This command provides a static snapshot of current processes at a single point in time. While it can show process resource usage, it lacks the real-time, continuously updating summary of overall system CPU and memory that top provides.

1. Check Point Gaia R81.20 CLI Guide: In the chapter "System Commands", the top command is described as the utility to "Display Linux processes". The example output clearly shows the summary header with CPU states (Cpu(s)), memory (Mem), and swap (Swap) statistics, followed by the list of individual processes with their resource utilization columns (%CPU, %MEM). (Reference: Check Point Gaia R81.20 CLI Guide, Page 198).

2. University of Illinois, CS 241: System Programming Courseware: Lecture notes on "Processes" describe standard Linux utilities. The top command is introduced as a tool that "shows you a sorted list of processes and vital statistics about the machine (e.g., uptime, memory, and CPU usage)." This confirms its dual role in showing both system-wide and per-process statistics. (Reference: CS 241, University of Illinois Urbana-Champaign, Fall 2021, Lecture 04: Processes, Slide 45).

3. Linux Programmer's Manual (man page): The official manual page for the top command, top(1), states in its description: "The top program provides a dynamic real-time view of a running system. It can display system summary information as well as a list of processes or threads currently being managed by the Linux kernel." (Reference: top(1) Linux manual page, DESCRIPTION section).