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Finding the Greediest Processes with topBog'liq linuxbasicsforhackersFinding the Greediest Processes with top
When you enter the
ps
command, the processes are displayed in the order
they were started, and since the kernel assigns PIDs in the order they have
started, what you see are processes ordered by PID number.
In many cases, we want to know which processes are using the most
resources. This is where the
top
command comes in handy because it dis
plays the processes ordered by resources used, starting with the largest.
Unlike the
ps
command, which gives us a onetime snapshot of the pro
cesses,
top
refreshes the list dynamically—by default, every 3 seconds.
You can watch and monitor those resourcehungry processes, as shown in
Listing 63.
kali >top
top - 15:31:17 up 2 days, 6:50, 4 users, load average: 0.00, 0.04, 0.09
Tasks: 176 total, 1 running, 175 sleeping, 0 stopped, 0 zombie
%Cpu(s): 1.3 us, 0.7 sy, 0.0 ni, 97.4 id, 0.0 wa, 0.0 hi 0.0 si 0.0
MiB Mem : 1491220 total, 64848 free, 488272 used, 938100 buff/cache
MiB Swap : 1046524 total, 1044356 free, 2168 used. 784476 avail MEM
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
39759 root 20 0 893180 247232 11488 S 0.7 16.6 1:47.88 ruby
39859 root 20 0 27308 16796 14272 S 0.3 1.2 1:47.88 postgres
39933 root 20 0 293936 61500 29108 S 0.7 4.1 1:47.88 Xorg
--snip--
Listing 6-3: Finding the greediest processes with top
System administrators often keep
top
running in a terminal to monitor
use of process resources. As a hacker, you may want to do the same, espe
cially if you have multiple tasks running on your system. While you have
top
running, pressing the H or ? key will bring up a list of interactive com
mands, and pressing Q will quit
top
. You’ll use
top
again soon to manage
your processes in “Changing Process Priority with nice” on page 65 and
“Killing Processes” on page 66.
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