Linux and Windows Interop files, user profiles and password profiles, user and group management

Linux and Windows inter-pass files
You can use tools Xshell or SECURECRT,
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Then install a package first: Lrzsz
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With the command
Yum Install-y Lrzsz

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Once the installation is complete, you can use the transfer command,
For example, we want to transfer files under Linux to Windows, which can be used with SZ filename:
SZ Y.txt
A dialog box pops up and we can choose to save the location desktop, and then we can view the file on the Windows desktop.

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If you want to upload files from Windows to Linux, use the RZ command.
For example: RZ Enter, this will pop up a dialog box, we choose to transfer the files to upload to the current directory.

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user profile and password configuration files
For example, the user's profile passwd, the user's other dedicated password file is called/etc/shadow, it and the user profile passwd is one by one corresponding, is specifically used to control the user's password, each creation of a user, it will add a line: File/etc/passwd, Every time you create a user, you add a line to the configuration file.
Command: CAT/ETC/PASSWD
If we create a user Yang, then at the bottom of the file, we'll add a line
Yang:x:1000:1000::/home/yang:/bin/bash

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We divide the user information into 7 segments:
The first section of Yang is the user name,
The second x represents the password,
The first 1000 of the third paragraph represents the user UID
The fourth paragraph, the second 1000 for GID,
The fifth paragraph: the comment information between and: represents the user does not have any substantive effect,
Sixth paragraph:/home/yang represents the user's home directory,
Seventh:/bin/bash represents the user's shell or a window that interacts with other users, both the normal user and the root shell are "/bin/bash", and the other user's shell is "/sbin/nologin", indicating that they cannot log on.
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Another file dedicated to the password is called/etc/shadow, which corresponds to the user profile passwd is one by one, is specifically used to store the user's password, each creation of a user, it will add a line:
Command: Ccat/etc/shadow
For example we create user Huang. The following message will appear
huang:!! : 17619:0:99999:7:::

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This used: divided into 9 segments
The first paragraph Huang is the user name,
The second paragraph!! The representative is the password, is ciphertext, cannot decompile,
The third paragraph 17619 represents the number of days, which is the distance from January 1, 1970 The last time the password change for this file is a few days away.
Fourth paragraph, 0 This paragraph indicates how many days to change the password again, if the value is 0 means the time is unrestricted,
The fifth paragraph 99999 of this paragraph indicates how many days after the password expires or if the password must be changed,
The sixth paragraph "7" this paragraph indicates the password expires before the warning time, specifically means that the password expires before the system 7 days to warn the user,
Seventh: Empty between and: Indicates the expiration date of the account
Eighth: Empty between and: represents the life cycle of an account
Nineth: null between and: Reserved field, no practical meaning
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User Management
/etc/group: User group Management files
When you create a user, you create a group that will have this line in the configuration file as long as you have this group.
/etc/gshadow: User group password file
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In the system, such as these configuration files are a file with a minus, this is the system to do the backup, if you accidentally deleted the configuration files, then you can copy these backups.

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Groupadd: Add Group

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Groupadd-g: Specify GID
Customization is best to specify more than 1000, because the system is reserved within 1000.

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Groupdel: Deleting a group (provided there are no users in the group)

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Let's try again. Delete a group that exists for the user try to delete

Obviously deleting a user's group is not possible.
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User Management
Create user
Command: useradd: New user

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When creating a user, specify its uid, GID, home directory, Shell
-U: Specify UID (not specified in case of previous user uid+1)
-G: Specify GID
-D: Specify home directory
-S: Specify Shell

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-M: Create a user without creating a home directory

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Userdel: Delete User (home directory is not deleted by default)
-R: Delete home directory at the same time

Linux and Windows Interop files, user profiles and password profiles, user and group management