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 chromeUSER - 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