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Rocky basics 1

2022-07-05 13:00:00 【51CTO】

1、 user

1)、 Administrators ：root ,uid : 0

2)、 Ordinary users ：1-60000 Automatically assigned

a、 System users ：1-999（centos7 in the future ）,1-499（centos6 before ）

b、 The logged in user ：1000+（centos7 in the future ）,500+（centos6 before ）

2、 User group

1)、 Administrators group ：root ,gid : 0

2)、 The normal group ：

a、 System group ：1-999（centos7 in the future ）,1-499（centos6 before ）, Allocate permissions to the resources obtained by the daemon

b、 The normal group ：1000+（centos7 in the future ）,500+（centos6 before ）, For users

3、passwd File format

      
      
       
       root:x:0:0:root:/root:/bin/bash
      
      
      
      
       
       1.

With ： Division

The first 1 Field ： Login name （ user ）

The first 2 Field ： password

The first 2 Field ：UID

The first 2 Field ：GID

The first 2 Field ： User description

The first 2 Field ： Home directory

The first 2 Field ： The user defaults to shell type

4、shadow File format

      
      
       
       root:$6$yHvOcFDvTFVaHdBH$9k3E8SBeDp86LBct5ml3Ih85q4VMKjutuNPUxQgdmPIwohH.wbjXPdrl4j4dGMQJB9TgyAJyWciI96W4D8GMp/:19176:0:99999:7:::
      
      
      
      
       
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With ： Division

User password : It's usually used sha512 encryption

from 1970 year 1 month 1 From the date of the last password change

The password can be changed in a few days (0 Can be changed at any time )

The password must be changed in a few days (99999 Never expire )

The system reminds the user a few days before the password expires （ Default to one week )

A few days after the password expires, the account will be locked

from 1970 year 1 month 1 Day count , How many days later the account will be invalid

example ： Generate random 10 Is password

       
       [[email protected] <sub>]
       
       #cat /dev/urandom |tr -dc '[:alnum:][email protected]#$%^' |head -c10
       
[email protected]
       
       #DS
       
[[email protected] </sub>]
       
       #openssl rand -base64 9
       
aNcISeq/BYIA
       
[[email protected] <sub>]
       
       #mkpasswd
       
v64y%FPzt
       
[[email protected] </sub>]
       
       #mkpasswd -l 9 -c 2 -C 2 -d 2 -s 2
       
       #5egg_6SV
       
       # notes ：-l 9  Representative length （9 Bit character password ）
       
       -c 
       
       2  For lowercase letters  （2 A lowercase letter ）
       
       -C 
       
       2  Represents capital letters  （2 For capital letters ）
       
       -d 
       
       2  On behalf of the digital  （2 Digit number ）
       
       -s 
       
       2  Represents a special symbol  （2 Bit special symbol ）
      
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5、 CD auto mount autofs

In the use of linux in , We have such a magical catalogue , It doesn't exist at ordinary times , Access automatic generation , then

Automatic disc mount On this directory , stay centos7 It's all about /misc/cd/ Catalog .

Need to install autofs service ：

      
      
       
       [[email protected] ~]
       
       #yum install -y autofs
      
      
      
      
       
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installed autofs Then check whether the service is enabled , If it's not turned on , It needs to be turned on

systemctl status autofs # see autofs service

systemctl start autofs # Turn on autofs

systemctl restart autofs # restart autofs

Get into /misc/cd I'll be surprised to find that there are CD-ROM files inside

       
       [[email protected] ~]
       
       #cd /misc/cd/
       
[[email protected] 
       
       cd]
       
       #ls
       
AppStream  EFI     isolinux  media.repo
       
BaseOS     images  LICENSE   TRANS.TBL
       
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