Linux under the PS command detailed

To monitor and control processes in the system, view status, memory,CPU usage, command:/bin/ps

(1) PS: is to show the status of the instantaneous process, not dynamic continuous;

(2) top: If you want to monitor the process running time, you should use the top command;

(3) Kill is used to kill the process or send a signal to the process;

(4) View the last man manual of the article to see the meaning of each output of PS toFind:standard FORMAT specifiers

===================================ps parameter Description =============================

l long format output;

U displays the process in the order of the user name and start time;

J Use the task format to display the process;

F to display the process in a tree-shaped format;

A shows all processes of all users (including other users);

X shows the process without control terminal;

R shows the running process;

WW avoids detailed parameters being truncated;

-A lists all processes
-W display widen to show more information
-au Show more detailed information
-aux Show all processes that contain other users

-e Show All Processes , environment variables
-F Full format
-H does not display the caption
-L Long format
-W Wide output
A shows all processes on the terminal , including other user processes
R shows only the running process
X shows no control of the terminal process

Our common options are the combination of aux or lax, and the application of parameter F.
PIDs lists only the process identifiers , separated by commas . The process list must be given immediately after the last option in the command line arguments , and no spaces can be inserted in the middle . For example:ps-f1,4,5 shows the process ID as the process of 1,4,5

The following describes the long command-line options , which begin with "--":
--sort x[+|-] key [, [+|-] key [,... ] ] Select A multi-letter key from the SORT keys section . + "characters are optional because the default direction is in ascending or dictionary order,"-"characters are sorted in reverse (that is, descending) .

For example: ps-jax-sort=uid,-ppid,+pid.
--HELP Displays help information .
--version Displays the version information for this command .

The sort key is mentioned in the previous option description and the sort key is further explained . It is important to note that the value used in the sorting is the intrinsic value of PS , not only for some output format pseudo -values. The list of sort keys is shown in the table below .

============ sort Key List==========================
C cmd executable simple name
C cmdline full command line
F Flags Long mode flag
G Pgrp Process Ground GroupId
G Tpgid ControlTTY Process GroupId
J Cutime Cumulative User Time
J Cstime Cumulative system time
K Utime User Time
K stime System Time
M Min_flt number of minor pages incorrectly
M Maj_flt Key page erroneously number
n Cmin_flt Cumulative Minor page error
N Cmaj_flt Cumulative Key page error
O Session DialogId
P PID ProcessId
P ppid Parent ProcessId
R RSS Resident Size
R Resident Resident Page
S size    memory size (Kbytes )  
S share    number of shared pages  
T tty   tty minor device number < Span lang= "en-US" > 
T start_time  process start time < Span lang= "en-US" > 
u uid   uid
u user    user name
V vsize    Total amount of virtual memory (byte ) &NBSP;
y priority  kernel scheduling priority
================================ ========ps aux  or  lax  output explanation =========================

2 . Explanation of PS aux or lax output

AU (x) output format :
USER PID%cpu%MEM VSZ RSS TTY STAT START time COMMAND

USER: Process Owner
PID: Process ID

%CPU: CPU Usage consumed
%MEM: Memory usage consumed
VSZ: The amount of virtual memory occupied
RSS: The amount of memory consumed

TTY: Secondary device number for the terminal (minor device numbers of TTY)

STAT: Process status :

Start: The time to start the process;
Time: How long the process consumes the CPU;
Command: The name and parameters of the commands;

========================================= process stat status ==================================

D a dormant state (usually IO process) that cannot be interrupted;
R is running in an interruptible queue;
S in hibernation, stationary state;
T stop or be traced, suspend execution;
W enters memory swap ( invalid starting from kernel 2.6);
X the process of dying out;
Z Zombie process does not exist but cannot be eliminated temporarily;

W: Not enough memory paging to allocate
Wchan the process resources being awaited;

<: high-priority process
N: Low Priority sequence process
L: Memory paged and locked in memory (instant system or I/O), that is , some pages are locked into memory

Leader of the S-process (under it there are sub-processes);
L multi-process (using clone_thread, similar to NPTL pthreads);
+ Process Group located in the background;

========================================kill Terminate process ================================

Kill terminates the process

There are more than 10 ways to control the process, here are some common methods :

kill-stop [PID]
Send SIGSTOP (17,19,23) to stop a process without destroying it.

Kill-cont [PID]
Send Sigcont (19,18,25) to restart a stopped process.

Kill-kill [PID]
Send SIGKILL (9) forces the process to stop immediately and does not implement a cleanup operation.

Kill-9-1
Stop all the processes you have.

SIGKILL and SIGSTOP signals cannot be captured, blocked, or ignored, but other signals can. So this is your ultimate weapon.

================================================== Example ==============================

$ ps
PID TTY Time COMMAND
5800 ttyp0 00:00:00 Bash
5835 TTYP0 00:00:00 PS
As you can see , the displayed items are divided into four items , which are PID (process ID),TTY (terminal name ),time (Process execution times ),command (the process-to-line input ).

You can use the u option to view the process owner and a little more detail , as follows:
$ ps U
USER PID%cpu%MEM USZ RSS TTY STAT START time COMMAND
Test 5800 0.0 0.4 1892 1040 Ttyp0 S Nov27 0:00-bash
Test 5836 0.0 0.3 2528 856 ttyp0 R Nov27 0:00 PS u

there is a horizontal line in front of the bash process , which means that the process is a user logging in to the shell, so there is only one process for a logged-on user with a dash . You can also see the%CPU,%mem two options , The former refers to the CPU time occupied by the process

And the total time in percent ; the latter refers to the amount of memory that the process occupies and the percentage of total memory .
In this case, you see all the control of the terminal process, of course, for other those who do not control the terminal process is not observed , so the need to apply the x option . The x option allows you to observe all process conditions .

1) PS a  shows all programs under the current terminal, including those of other users.
2) ps-a  Show All Programs.
3) PS c  displays the actual instruction name of each program, without the indication of the path, parameter, or resident service when listing the program.
4) ps-e  The effect of this parameter is the same as specifying
5) PS e  Displays the environment variables used by each program when the program is listed.
6) PS f  uses ascii characters to display the tree structure, expressing the relationship between the programs.
7) ps-h  displays a tree structure that represents the inter-program relationship.
8) ps-n  shows all programs except the program that executes ps command terminal.
9) PS s  shows the program status in the format of the program signal.
) PS s  lists programs, including interrupted sub-program data.
One) ps-t< terminal number >  specifies the terminal number and lists the status of the program belonging to that terminal.
) PS u  Displays the status of the program in a user-oriented format.
) PS x  shows all programs, not differentiated by terminal.

The most common method is ps-aux, and then directed to grep with the pipe symbol to find a specific process