TOP command examples on Linux to monitor processes

for more information, visit
http://www.binarytides.com/linux-top-command/

$ top

top - 18:50:35 up  9:05,  5 users,  load average: 0.68, 0.52, 0.39
Tasks: 254 total,   1 running, 252 sleeping,   0 stopped,   1 zombie
%Cpu(s):  2.3 us,  0.5 sy,  0.0 ni, 97.1 id,  0.2 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:   8165300 total,  6567896 used,  1597404 free,   219232 buffers
KiB Swap:  1998844 total,        0 used,  1998844 free.  2445372 cached Mem

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND             
17952 enlight+  20   0 1062096 363340  88068 S   4.8  4.4   0:49.33 chrome              
14294 enlight+  20   0  954752 203548  61404 S   2.1  2.5   2:00.91 chrome              
 1364 root      20   0  519048 105704  65348 S   0.6  1.3  17:31.27 Xorg                
19211 enlight+  20   0  576608  47216  39136 S   0.6  0.6   0:01.01 konsole             
   13 root      rt   0       0      0      0 S   0.3  0.0   0:00.10 watchdog/1          
   25 root      20   0       0      0      0 S   0.3  0.0   0:03.49 rcuos/2             
 1724 enlight+  20   0  430144  36456  32608 S   0.3  0.4   0:03.60 akonadi_contact     
 1869 enlight+  20   0  534708  52700  38132 S   0.3  0.6   0:53.94 yakuake             
14040 enlight+  20   0  858176 133944  61152 S   0.3  1.6   0:09.89 chrome

USER - The system user account running the process.
%CPU - CPU usage by the process.
%MEM - Memory usage by the process
COMMAND - The command (executable file) of the process

Display full command path and arguments of process - 'c'

Press 'c' to display the full command path along with the commandline arguments in the COMMAND column.

%CPU %MEM     TIME+ COMMAND                                                    
  0.0  0.0   0:00.00 /usr/bin/dbus-launch --exit-with-session /usr/bin/im-laun+ 
  0.0  0.1   0:01.52 /usr/bin/dbus-daemon --fork --print-pid 5 --print-address+ 
  0.0  0.3   0:00.41 /usr/bin/kwalletd --pam-login 17 20                        
  0.0  0.0   0:00.00 /usr/lib/x86_64-linux-gnu/libexec/kf5/start_kdeinit --kde+ 
  0.0  0.3   0:01.55 klauncher [kdeinit5] --fd=9                                
  0.0  0.2   0:00.13 /usr/lib/telepathy/mission-control-5                       
  0.0  0.1   0:00.00 /usr/lib/dconf/dconf-service                               
  0.0  0.4   0:01.41 /usr/lib/x86_64-linux-gnu/libexec/kdeconnectd              
  0.0  0.2   0:01.09 /usr/lib/x86_64-linux-gnu/libexec/kf5/kscreen_backend_lau+

Display all CPU cores - '1'

Pressing '1' will display the load information about individual cpu cores. Here is how it looks -

top - 10:45:47 up  1:42,  5 users,  load average: 0.81, 1.14, 0.94
Tasks: 260 total,   2 running, 257 sleeping,   0 stopped,   1 zombie
%Cpu0  :  3.6 us,  3.6 sy,  0.0 ni, 92.9 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu1  :  3.1 us,  3.6 sy,  0.0 ni, 93.3 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu2  :  7.6 us,  1.8 sy,  0.0 ni, 90.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu3  :  9.6 us,  2.6 sy,  0.0 ni, 87.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:   8165300 total,  7118864 used,  1046436 free,   204224 buffers
KiB Swap:  1998844 total,        0 used,  1998844 free.  3410364 cached Mem

Batch mode

Top also supports batch mode output, where it would keep printing information sequentially instead of a single screen. This is useful when you need to log the top output for later analysis of some kind.

Here is a simple example that shows the Cpu usage at intervals of 1 second.

$ top -d 1.0 -b | grep Cpu