Linux process management and shell scripting

Use! To invoke past commands.

!! Repeat the previous instruction

!a Repeat the previous instruction, led by a

!nubmer Repeat the previous instruction to record numbers in the history table

!-number Repeat the previous number instruction

Ailas abc= ' CD xxxxxxxxxxx/xxxxxxxx/xxxxxxxxxxxxx '

Unalias ABC

"" To see a string of characters as strings, you can translate special characters

" the character cannot be translated as a string.

• Ability to return results from command execution

Echo ' Uname-a '

Mathematical operations

$[] expressions within brackets are mathematically calculated

escape character \

Special meaning for canceling characters in the command line

Used to indicate the end of a line

end character ;

child Shell Activation Command ()

logical operators

&& Execute the following command after the execution of the current instruction is successful

|| The following command is executed after the execution of the current instruction fails

Login Shell

by default, the variable is changed underthe shell, Umask,alias is only valid for this login, and the default value will be restored once it is logged out. You need to change the configuration file for permanent entry.

Custom Landing Shell

Global settings file /etc/profile

/etc/bashrc

user settings file ~/.BASHRC

~/.profile

source./bash_profile Execution Environment variables

CTRL -D input has ended.

System Monitoring

uname Display System Information uname-a

Hostname Display host name hostname a change the hostname to a (temporary) if you want to change the configuration file permanently /etc/sysconfig/network

last list of recently logged in users

Lastlog List The user's last logon time and login terminal address

Free Check memory condition

Top Task Manager

Process

Instructions for querying a process

PS option ps-ef lists all processes of the current system Psaux

Pstree to display process relationships in a tree-like manner

Control process

Kill- Signal file

Kill-9 forced termination

Pkill Process Name

Kill sleep// equivalent to Ps-ef |grep sleep |awk|xargs|kill

Killall httpd// kills all processes, kills all http processes

the priority of the process, represented by a nice value

Nice with a nice value to run command nice-nnum command

Renice Changing the nice value of a running process

Renice-n PID

Nohup SH executes scripts in the background

Ctrl Z hangs a foreground process

FG Job Number The file foreground runs the BG job number to run the file background

/proc Directory

Shell Scripts Script

a shell script is a text file that contains a shell directive

Shell and oh ah this supports variables with simple syntax to complete batch work

How shell scripts support interaction, reading data from standard input at execution time

some of ING 's system work is done through shell scripting, such as system boot, service control.

Edit Shell script

General use VI Edit Script. Starting with # in the script indicates that the line is commented.

the first character of a script if the non- # representation is a bash script

The first character of a script if it is

in shell and Shell scripts, we allow ourselves to define variables and assign them values

Grammar variable Name = value

Export variable name variable becomes environment variable

Unset to cancel a variable definition

to read data into a database using read

Read username from standard input read-p "please xxxxxxx": U1

echo Output

run the shell script

SH path / script name

/ Path / script name

./ Path / script name

Conditional judgment

If condition ["$pass" = ' hostname '];

Then

elif conditions

Then

Else

Action

Fi

Case Expression in

Match value 1)

action ;;

Match Value 2)

action ;;

Esac

For variable in array

Do

Action

Done

While condition

Do

Action

Done

Until conditions

Do

Action

Done

X window System