Linux command “top”

Tasks 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)

CPU information:

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)

Processes information:

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)

Useful commands:

k – Allows you to “kill” a process providing his pid
r – This allows you to renice a process providing his pid
u – This will display only the processes of a user
F – Select sort field

Shortcuts at the time of running top command

l –To display or to hide load average line
t –To display or to hide task/cpu line
1 –To display or hide all other CPU’s
m –to display or to hide RAM and SWAP details
s –To change the time interval for updating top results(value is in sec’s)
R –To sort by PID number
u — Press u then username to get only that user process details
P –To sort by CPU utilization
M –To sort by RAM utilization
c –To display or hide command full path
r –To renice a process, press r then the PID no then the renice value to renice a process.
k –To kill a process, press k then PID number then enter to kill a process
w –To save the modified configuration permanently.
q –To quit the top command.
h –for getting help on top command

For htop:

Arrow keys – move around and select a process

F6 – Choose “sort by”
F7 – Remove priority to selected process (renice)
F8 – Add priority to selected process
F9 – Kill the select process

Get the top 10 CPU consuming process

ps aux | sort -n -k 3 | tail -10

Get the top 10 memory consuming process

ps aux | sort -n -k 4 | tail -10
Reference:

http://linuxaria.com/howto/understanding-the-top-command-on-linux
http://linuxaria.com/article/monitoring-process-top-htop?lang=en

Processes and CPU information (top)