"Four famous catches" of Linux process management

One or four famous arrests

The four famous arrests, which first appeared in the martial arts novels written by Wen Ruian, are the four apprentices of Zhuge Xiaohua, the righteous force in the court. The amazing "chasing life" of leg work and the first-class "cold blood" of swordsmanship.

The four famous catches in this article were starred by the linux command:

Relentless: ps starred

Iron hand: dstat starred in pursuit
: top starred
cold blood: htop starred

2. Basic knowledge related to the process

Before introducing the four famous catches, let me introduce the basic knowledge related to the process.

3. Master of Light Power Hidden Device "Relentless" [PS]

ps: used to display the status of the current process (non-dynamic)
ps [options]:

There are three styles of options:
1. UNIX style, "-" must be added before the option
2. BSD style, "-" cannot be added before the option
3. GNU style, two "-" before the option

One of the commonly used combinations: aux

a: All processes related to the terminal
x: all processes not related to the terminal
u: User-centered process status information display

CPU%: CPU time occupancy rate

MEM%: memory usage percentage

VSZ: virtual size virtual memory set;

RSS: Resident Size, resident memory set;

STAT：

R: running
S: interruptable sleeping
D: uninterruptable sleeping
T: Stopped
Z: zombie
+: Foreground process
l: multi-threaded process
N: low priority process
<: High priority process
s: session leader process leader

Common combination two: -ef

-e: show all processes
-f: display process information in full format

Commonly used combination three: -eFH

-F: Display process information in complete format;

C: cpu utilization cpu occupancy percentage
PSR: Which CPU to run on

-H: Display the relevant information of the process in a hierarchical structure;

Four common combinations: -eo, axo

o field1, field2,…: custom list of fields to be displayed, separated by commas

Commonly used fields: pid, ni, priority, psr, pcpu, stat, comm, tty, ppid, rtprio

pid: the pid number of the process
ni: nice 值
priority: priority
psr: running on that CPU
pcpu: cpu utilization
ppid: the id number of the parent process
rtprio: real-time priority

Fourth, the master of excellent internal skill "iron hand" [dstat]

dstat: System resource statistics command (dynamic)
dstat [-afv] [options ..] [delay [count]]

Common options:

-c, -cpu: display cpu related information;
-C #, #,…, total: display the first CPU, the second CPU or the total
-d, --disk: display disk related information
-D sda, sdb, ..., tobal: display the specified hard disk device, total space
-g: display page-related rate data;
-m: Memory related statistics
-n: related statistical data of Interface;
-p: display relevant statistical data of process;
-r: display statistics related to io requests;
-s: display related statistics of swapped;

–Tcp: display tcp socket

–Udp: show udp connection

--Raw: show raw sockets

–Socket: socket

–Ipc: interprocess communication information

--Top-cpu: displays the most CPU-intensive processes;

–Top-io: the process that occupies the most io;

--Top-mem: the most memory-intensive process;

Fifth, the amazing "chasing life" [top]

top: List inux processes
top as the dynamic display process

The specific meaning of the parameters of the top command:

top – 14:58:34 up 5:28, 1 user, load average: 0.01, 0.02, 0.05

14:58:34: Current time
up 5:28: running time
1 user: the number of users logging in the current system
load average: 0.01, 0.02, 0.05: average load (load of queue length waiting to run)

Tasks: 353 total, 2 running, 351 sleeping, 0 stopped, 0 zombie