Linux Note II: System User Management

User Category:

Administrators group:

Normal Group:

System Group:

General Group

User Group Category:

Private group: Create a user, create a group with the same name by default if the owning group is not specified

Basic group: Default group for users

Additional groups, additional groups: Default groups for other groups

User:

/etc/passwd

Account

passwd

Uid:

Gid:

Comment

HOME DIR:

SHELL:

/etc/shadow

Account

Encrypted password:

User management:

useradd [option] USERNAME

-U UID

-G GID (Basic Group)

-G GID, .... (Additional groups)

-C Comment Information

-D Home Directory

-S SHELL

-m-k

-M do not create home directory

-R Add a system user

/etc/login.defs

Userdel [option] USERNAME

-R: Colleague deletes user's home directory

ID: View user's account attribute information

Usermod

-L: Modify login Name

-L: Lock account

-U: Unlock Account

CHSH: Modifying the user's default shell

CHFN: Modifying annotation information

Password management

passwd [USERNAME]

--stdin standard input Read password

-L

-U

-D Delete User password

PWCK: Checking user account Integrity

Group Management:

To create a group:

Groupadd

-G: Specify GID

-R: Add a system Group

Groupmod

-g:gid

-n:grpname

Groupdel

GPASSWD: Setting a password for a group

NEWGRP: Temporary switch Group (exit exit)

Chage

-D: Most recent modification time

-E: Expiration time

-I: Inactive time

-M: Minimum period of use

-M: Maximum lifespan

-W: Warning time

Rights Management:

Chown: Change file owner (only administrators can use this command)

#chown USERNAME file, ....

-R: Modify the owner of the directory and its internal files

--reference=/path/to/somefile file,... Reference a file, set the same as the reference file

Chown username:grpname file, .... (USERNAME. GRPNAME) Change the genus Group at the same time

#chgrp GRPNAME file, ...

-R: (Recursive)

--reference=/path/to/somefile file,... Reference a file, set the same as the reference file

chmod: Modify permissions for a file

Modify the permissions of the three categories of users;

chmod MODE file, ....

-R: (Recursive)

--reference=/path/to/somefile file,... Reference a file, set the same as the reference file

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Linux Note II: System User Management