Let’s see now every single row of this output to explain all the information found within the screen.
1° Row — top
This first line indicates in order:
current time (11:37:19)
uptime of the machine (up 1 day, 1:25)
users sessions logged in (3 users)
average load on the system (load average: 0.02, 0.12, 0.07) the 3 values refer to the last minute, five minutes and 15 minutes.
2° Row – task
The second row gives the following information:
Processes running in totals (73 total)
Processes running (2 running)
Processes sleeping (71 sleeping)
Processes stopped (0 stopped)
Processes waiting to be stoppati from the parent process (0 zombie)
3° Row – cpu
The third line indicates how the cpu is used. If you sum up all the percentages the total will be 100% of the cpu. Let’s see what these values indicate in order:
Percentage of the CPU for user processes (0.3%us)
Percentage of the CPU for system processes (0.0%sy)
Percentage of the CPU processes with priority upgrade nice (0.0%ni)
Percentage of the CPU not used (99,4%id)
Percentage of the CPU processes waiting for I/O operations(0.0%wa)
Percentage of the CPU serving hardware interrupts (0.3% hi — Hardware IRQ
Percentage of the CPU serving software interrupts (0.0% si — Software Interrupts
The amount of CPU ‘stolen’ from this virtual machine by the hypervisor for other tasks (such as running another virtual machine) this will be 0 on desktop and server without Virtual machine. (0.0%st — Steal Time)
4° and 5° Rows – memory usage
The fourth and fifth rows respectively indicate the use of physical memory (RAM) and swap. In this order: Total memory in use, free, buffers cached. On this topic you can also read the following article
Following Rows — Processes list
And as last thing ordered by CPU usage (as default) there are the processes currently in use. Let’s see what information we can get in the different columns:
PID – l’ID of the process(4522)
USER – The user that is the owner of the process (root)
PR – priority of the process (15)
NI – The “NICE” value of the process (0)
VIRT – virtual memory used by the process (132m)
RES – physical memory used from the process (14m)
SHR – shared memory of the process (3204)
S – indicates the status of the process: S=sleep R=running Z=zombie (S)
%CPU – This is the percentage of CPU used by this process (0.3)
%MEM – This is the percentage of RAM used by the process (0.7)
TIME+ –This is the total time of activity of this process (0:17.75)
COMMAND – And this is the name of the process (bb_monitor.pl)
