top Command: Tutorial & Examples

Display the top running processes

The top command is a real-time system monitoring tool that displays a dynamic view of the system's processes and resource usage. It shows a list of the currently running processes, along with information about their CPU and memory usage, priority, and other details.

To start top, simply type top at the command prompt. By default, top updates the display every few seconds and sorts the process list by CPU usage.

top

Here is an example of the top command's output:

top - 13:46:57 up 150 days,  4:03, 11 users,  load average: 3.75, 3.95, 3.54
Tasks: 307 total,   1 running, 306 sleeping,   0 stopped,   0 zombie
%Cpu(s):  7.8 us,  0.8 sy,  0.0 ni, 91.0 id,  0.1 wa,  0.0 hi,  0.3 si,  0.0 st
MiB Mem :  64305.6 total,    999.9 free,  41519.1 used,  21786.5 buff/cache
MiB Swap:   3796.0 total,   1856.5 free,   1939.5 used.  22067.4 avail Mem

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
   8165 mysql     20   0  983.1g  33.8g   8044 S 105.0  53.9 567144:43 mysqld
  16058 root      20   0 6437408 466308   8096 S   9.6   0.7   5411:24 java
 791477 root      20   0 6692620 313092  17928 S   6.0   0.5  36:58.26 java
2605714 root      20   0   10.7g   1.2g  12996 S   6.0   2.0 967:52.13 java
2520408 root      20   0 5893648 342000  11952 S   4.0   0.5 599:09.46 java
 914650 root      20   0 7110816   1.2g   8404 S   2.0   1.9  39952:51 java
3050519 root      20   0   13236   8196   6220 S   2.0   0.0 806:16.58 ssh
  13850 root      20   0 4963988 328148  16588 S   1.7   0.5  66:15.43 java
 933092 root      20   0 7438060 476816   2484 S   1.0   0.7   2755:54 java
 889630 root      20   0       0      0      0 I   0.3   0.0   0:00.05 kworker/u64:15-kcryptd/253:0
 890189 root      20   0   10180   3980   3248 R   0.3   0.0   0:00.02 top

As you can see, the mysql process is the first in the list as is uses the most CPU time. It also uses about half of the available RAM.