Top

top command is used to show the Linux process and it provides a real-time view of the running system
This command shows the summary of information of the system and list of processes or threads which are currently managed by the Linux Kernel.
When the top command is executed then it goes into interactive mode and we can exit by pressing q

Basic Syntax¶

Start top:

      top

  Do not show any idle or zombie processes:

      top -i

  Show only processes owned by given user:

      top -u username

  Sort processes by a field:

      top -o field_name

  Show the individual threads of a given process:

      top -Hp process_id

  Show only the processes with the given PID(s), passed as a comma-separated list. (Normally you would not know PIDs off hand. This example picks the PIDs from the process name):

      top -p $(pgrep -d ',' process_name)

  Get help about interactive commands:

      ?

The output of ps in Terminal returns,

PID : shows task's unique process ID
USER : username of the owner of the task
PR : shows the scheduling priority of the process from the perspective of kernel
NI : represents the Nice Value of the task. A negative value implies higher priority.
VIRT : total virtual memory used by the task.
RES : memory consumed by the process in RAM
SHR : represents the amount of shared memory used by the task.
S : this field shows the process state in the single-letter form
%CPU : CPU usage
%MEM : memory usage of the task
TIME+ : CPU time

Other Examples¶

Shows tasks by username
```
top -u userName
```
Show commands absolute path : top then press c
Kill a process by PID within the session : top then pres K
Sort all Linux running commands by memory usage : top then M and P