Linux account and Rights management commands

Linux user accounts are divided into:

Super User root (uid 0)

Normal User (UID 500 and above)

Program User (UID 1-499)

Group account:

Basic Group (Private group)

Additional groups (public groups)

/etc/passwd

Save the user name, host directory, login shell and other basic information, each line corresponding to one user's account records, seven fields

Example: Teacher:x:500:500:teacher:/home/teacher:/bin/bash

Field meaning: User name: Password placeholder: uid:gid: User description: Host directory: Login Shell

/etc/shadow

Save the user's password, account validity and other information, each line corresponding to a user's password record, nine fields

Field meaning: User name: encrypted password: Last modified password time: Minimum validity: Maximum validity: Early expiration warning: Days after password expires: Account expiration: Reserved field

Useradd Add user account

-u: Specify UID tag number

-D: Specify the host directory, default to/home/user name

-e: Specify the account expiration time

-G: Specify the user's base group name (or UID number)

-G: Specify the user's additional group name (or GID number)

-M: Do not establish and initialize the host directory for the user

-S: Specify the user's login shell

Initial profile of user account (template/etc/skel)

~/.bash_profile: Executed every time the user logs on

~/.BASHRC: Execute every time you enter a new bash environment

~/.bash_logout: The user executes each time they log out

passwd Change your account password

-D: Clear the user's password so that it can log in and delete the user account without a password Userdel

-L: Lock user account

-S: Check the status of the user account (whether locked)

-U: Unlock user account

Usermod modifying the properties of a user account

-L: Change the login name of the user account

-L: Lock user account

-U: Unlocking user accounts

The following options have the same meaning as in the Useradd command

-U,-D,-e,-G,-G,-S

Userdel Delete user account

-R: Indicates that the user's host directory is deleted

Group account Files

/etc/group: Save group account basic information

/etc/gshadow: Save password information for group account

Groupadd Add a group account

GPASSWD Set group account password (rarely used), add/Remove Group members

-A: Adding a user to a group

-D: Delete a user member from within a group

-M: Defines a list of group members, separated by commas

Enquiry Account Information

ID Command Query user identity

The groups command queries the group to which the user belongs

Users, W, who commands query for user information that is logged on to the host

Permissions and attribution of files/directories

Access rights

Read R:4 allows viewing of file contents, displaying directory listings

Write W:2 allows you to modify the contents of a file, allowing new, moved, deleted files or subdirectories in the directory

Execute x:1 allows you to run programs, switch directories

Attribution (ownership)

Owner: The user account that owns the file or directory

Group: An account number that owns the file or directory

chmod setting permissions for files and directories

Format: chmod [Ugoa] [+-=] [rwx] file or directory ...

or chmod nnn file or directory ...

Chown setting the attribution of files and directories

Format: chown: Genus group File or directory

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Linux account and Rights management commands