Linux users, group accounts, and permissions (Learn note nine)

First, the user classification

• Super User: Root
• Normal User: Created by Superuser and administrator, generally only have full permissions in their own directory
• Program Users:

Second, user account management

Common commands:

Useradd: Adding users

Userdel: Deleting users

passwd: Set User password

Groupadd: Add group account

Groupdel: Delete group account

GPASSWD: Add/Remove Group members

2.1.useradd: Add user

Tar] # useradd  20150222  test1       tarpasswd for   Short  passwdtar]# useradd test2

2.2.Userdel: Delete User

Tar] # Userdel Test2-tarls -l/home/4drwx44096  - :tar

2.3. PAPASSWD: Set User password

[[Email protected]Tar]#passwd-S test1test1 PS -- Geneva- + 0 99999 7-1(Password set, SHA512 crypt.) [[Email protected]Tar]#passwd-l test1locking Password foruser test1.passwd: Success[[email protected]Tar]#passwd-S test1test1 LK -- Geneva- + 0 99999 7-1(Password locked.) [[Email protected]Tar]#passwd-u test1unlocking Password foruser test1.passwd: Success[[email protected]Tar]#passwd-S test1test1 PS -- Geneva- + 0 99999 7-1(Password set, SHA512 crypt.) [[Email protected]Tar]#passwd-d test1removing Password foruser test1.passwd: Success[[email protected]Tar]#

2.4. Groupadd: Add group account

[[Email protected] ~

2.5, Groupdel: Delete group account 2.6. GPASSWD: Add/Remove Group members

[Email protected] ~~]# gpasswd-~]# gpasswd-~

2.7 User Group modifications

-N  new_group_name old_ group_name

2.8. View the current user group

Groups

2.9. Modify user Information

To modify the user Information command:
[[email protected] opt] #usermod parameter user name
Parameters:
-C Description
-G Group name Initial user group
-E Expiration date format: YYYY-MM-DD
-G group name other user groups
-L Modify User name
-L Lock Account (two exclamation mark in front of user's password password string in/etc/shadow file) ）
-U unlock

Third, the Authority

[Email protected] documents]#ls-Altotal thedrwxr-xr-x.7Root root4096Feb -  on: the. Dr-xr-x---. -Root root4096Feb -  -:xx ..-rw-r--r--.1Root root AboutFeb +  at: theA.TXTDRWXR-xr-x.4Root root4096Feb - xx: +com-rw-r--r--.1Root root148Feb -  on: atC.Tar. GZ-rw-r--r--.1Root root theFeb -  on: theC.txt-rw-r--r--.1Root root -Feb -   -file1.txt.gz-rw-r--r--.1Root root34419Feb - xx: -HTTPD.CONFDRWXR-xr-x.3Root root4096Feb -  on: the Tar-rw-r--r--.1Root root inFeb -   -TESTDRWXR-xr-x.4Root root4096Feb +  A: -TEST1DRWXR-xr-x.2Root root4096Feb +  A: +test4-rw-r--r--.1Root root theFeb -  on: +Test4.Tar. GZDRWXR-xr-x.4Root root4096Feb -   -Tests[[email protected] documents]#

The columns of the list are defined as follows:
[Permission Property Information] [Number of connections] [owner] [owner-owned user group] Size [Last Modified time] FileName

The permission attribute list is 10 characters:
The first character indicates the file type, D is the directory-for normal file L for connection b for the storage interface device C for keyboard and mouse input device
2, 3, 4 characters represent owner permissions, 5, 6, 7 characters represent owner-group user Rights, 8, 9, 10 for other user rights

The second character represents the owner Read permission, or R if there is permission, or-
The third character represents the owner write permission, or W if there is permission, or-
The fourth character represents the owner execution permission, or X if there is a permission, or-
The fifth character indicates that the owner is in the same group as the user Read permission, if the permission is R, no permission is-
The sixth character indicates that the owner is the same as the group user write permission, if the permission is W, no permission is-
The seventh character indicates that the owner performs the permissions with the group user, and if the permission is x, no permission is-
The eighth character represents other non-identical read permissions, and if there is a permission R, no permission is-
The nineth character represents the other non-identical write permissions, if the permission is W, no permission is-
The tenth character represents the other non-identical group execution permissions, if the permission is x and no permission is-

Iv. Representation of permissions

Digital form and character form

R, W, X can be represented by octal 4,2,1, which, when represented by a combination, need to add numbers.

Five, permission setting chmod 5.1. chmod [Ugoa ...] [+-=] [rwx] File or directory

Ugoa: For the user class, u represents the owner of the file, G represents the user in the user group where all the files are located, o any other user, a represents all users (u,g,o sum)

+-=: Set the action of the permission, + means to increase the appropriate permissions, minus the corresponding permissions, = means to set the appropriate permissions only

RWX: The character combination of permissions, which can be used either individually or in combination such as: R,W,X,RW,RX,WX,

5.2, chmod nnn file or directory

5.3 chmod-r Options

Add-r option to set subdirectories under directory, files to the same permissions

vi. setting file Attribution

Chown: Can be set to owner, belong to group

Chgrp: Modify the genus group only

So chown often use

6.1, Chown

Chown owner [: [Genus]] file or directory

Set-up at the same time: delimited

If a group is set individually, group: genus

Linux users, group accounts, and permissions (Learn note nine)