Pode usar o comando top
top - 13:19:02 up 2:47, 1 user, load average: 0.92, 0.92, 0.95
Tasks: 271 total, 2 running, 267 sleeping, 0 stopped, 2 zombie
Cpu(s): 26.6%us, 12.4%sy, 0.0%ni, 60.3%id, 0.3%wa, 0.0%hi, 0.3%si, 0.0%st
Mem: 2064932k total, 1546096k used, 518836k free, 43880k buffers
Swap: 9868284k total, 36256k used, 9832028k free, 589124k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
13077 www-data 20 0 82236 17m 9492 R 46 0.9 1:50.24 php
2060 mysql 20 0 314m 36m 3064 S 10 1.8 16:07.45 mysqld
2063 root 20 0 71560 30m 14m S 7 1.5 9:22.77 Xorg
5620 arthur 20 0 264m 15m 11m S 5 0.8 0:03.25 mate-terminal
10874 arthur 20 0 320m 34m 15m S 4 1.7 2:17.54 transmission-gt
5607 arthur 20 0 238m 72m 32m S 2 3.6 2:01.14 chrome
5312 arthur 20 0 858m 150m 37m S 2 7.5 9:21.39 chrome
3862 arthur 20 0 255m 13m 10m S 1 0.7 0:03.14 clock-applet
13170 root 20 0 2824 1108 780 R 1 0.1 0:00.27 top
10 root 20 0 0 0 0 S 0 0.0 0:07.29 ksoftirqd/1
1972 mongodb 20 0 91252 1752 1496 S 0 0.1 0:53.38 mongod
3792 arthur 20 0 277m 15m 8648 S 0 0.8 0:08.98 python
3974 arthur 20 0 461m 46m 14m S 0 2.3 0:21.59 dropbox
13034 root 20 0 0 0 0 S 0 0.0 0:00.40 kworker/0:0
1 root 20 0 3936 2068 1248 S 0 0.1 0:01.57 init