Linux Learning Note Four

Unit V

########################## User Action command #################

(i) use of ID

ID user name # # View user Information

Id-u # # # user uid(userid)

-G # # user gid(initial group ID, only one)

-A # # user All information

-G # # User ID for all groups (including university,Linux Group, etc.)

-un # # # User name

-gn # # # User Initial group name

-gn # # # users all group names

Execute vim/etc/login.dafs, the user's uid default is !

650) this.width=650; "Src=" Http://s5.51cto.com/wyfs02/M00/88/45/wKioL1ftGHfRKs59AACqPLWqBz8616.png-wh_500x0-wm_3 -wmp_4-s_3622819962.png "title=" image 1.png "alt=" Wkiol1ftghfrks59aacqplwqbz8616.png-wh_50 "/>

The operating conditions are:

[Email protected] desktop]$ echo $PATH

/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin

[[email protected] desktop]$ which LS

Alias ls= ' ls--color=auto '

/usr/bin/ls

(ii) Switch User's environment

Echo $PATH # # # View the user environment for the current user, which displays the current PATH environment variable, which consists of a series of colon-delimited directory names.

Echo $USER # # # Displays information about the current user

su-username### Switching the environment used by the current user

# #kiosk原本的环境

[Kiosk Echo $PATH

/usr/local/bin:/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/home/kiosk/.local/bin:/home/kiosk/bin

# #root原本的环境

[Root Echo $PATH

/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

# #root用su-kiosk Switch to kiosk while switching to Kiosk's own environment variable

[Root Su-kiosk

[Kiosk Echo $PATH

/usr/local/bin:/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/home/kiosk/.local/bin:/home/kiosk/bin

# #root用su Kiosk switches to kiosk, but still root path, no path to the kiosk

[Root su Kiosk

[Kiosk Echo $PATH

/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

The difference between SU student and su-student when switching users :

1.su-student Switch User, and user's environment, add "-" environment variable also changed;

2. do not add "-" that is, su student just switch users.

(iii) actions for users and Groups

1. User

① User Type

A. administrator Root: A user with all permissions,the value ofuid is 0

B. Normal User: Normally created user,uid is ~60000

C. system users: To ensure that the system operation of users, generally do not provide password login system,the UID is 1~499

② user-related files

A./etc/passwd## user Information file

stores the user's basic properties, from which all users of Linux can be viewed . The format is:

"User name: Password: User ID: Owner group ID:user description (e.g. name, age, phone, etc.): User root: User programming environment ( Shell used ) "

Each user group has one primary group (private group), one or more additional groups.

B./etc/shadow## user authentication information

Some strategies for storing user passwords in the form of:

"User name: Password: the date of the most recent password change: The number of days the password cannot be changed: Warning period before password change: Password expiration Grace time: Account expiration Date: Reserved"

C./home/username## user home directory

D. basic information configuration for/etc/skel/.*## users

③ User Commands

A. new User:useradd-d root- G Primary Group - G additional group list (comma separated) user name

B. Reset Password:passwd user name

C. Modify User:usermod-d root- G Primary Group - G additional group list (comma separated) user name ———— the command- G will move the user from the original additional group, you can use the- a parameter to indicate that the new mode

D. deleting a User:userdel-r Delete a user name together with the root directory

E. View all users:cat/etc/passwd

F. viewing individual user details:ID user name

G. view all currently logged-in users:WHHO

2. User Groups

The user group is the user's container, and the user can inherit permissions from the user group.

① User Group Type

A. common user groups: can join multiple users

B. System user group: Generally add some system users

C. Private user group: When a user is created, a user group with the same name will be created for that user if no user group is indicated. A private user group is actually a common user group.

② user group related files

A./etc/group## user group information

Basic information about the storage group. The format is;

"group name: Group Password: group ID: User list"

B./etc/gshadow

similar to the shadow of the user group

③ User Group Commands

A. new group:groupadd-g uid number group name ———— automatically generated if the uid number is not specified

Groupadd-g 888 Test(Specify uid as 888)

Groupadd hehe(uid not specified )

B. modify group:gruopmod-n new group name ———— can be used to group names

Groupmod-n Jack Jaak

C. Delete Group:groupdel Group name ———— cannot be deleted if there are users in the group

D. View all Groups + view users within a group:cat/etc/gruop

E. viewing the user's group information:ID user name

Output:

Uid=0 (Root) gid=0 (root) groups=0 (root)

UID is the primary group,gruops is the additional group

F. adding users to a group:gpasswd-a user name Group name

G. removing a user from a group:gpasswd-d user name Group name

-----------------------------------------------------------------

(iv) detailed operation of the user

useradd### New User

-u### The UID of the specified user

-g### Specify user initial group, this group must exist

-g### Specify additional groups, the same group must exist

-c### User Description

-d### Specify user plus directory

-s### Specify the shell that the user uses ,shell type See /etc/shells

userdel-r#### Deleting a user

groupadd-g### New Group,-g indicates the ID of the specified group

groupdel### Deleting a group

passwd#### Changing user passwords

"Example"useradd-u 1016(existing group number) - G 1016(existing group number) test(user name)

650) this.width=650; "Src=" Http://s3.51cto.com/wyfs02/M01/88/45/wKioL1ftGJ-gdgv1AAEsa5ZA_aM324.png-wh_500x0-wm_3 -wmp_4-s_2998973060.png "title=" image 2.png "alt=" Wkiol1ftgj-gdgv1aaesa5za_am324.png-wh_50 "/>

################## First, listen passwd . ###########

Watch-n1 Tail-n 3/etc/passwd

1.

Useradd Add test User

Useradd Test

When a process is in use and cannot delete test :

Kill + The process number

And then again:

Userdel-r Test

So that we can remove it successfully.

650) this.width=650; "Src=" Http://s3.51cto.com/wyfs02/M02/88/49/wKiom1ftGK2A0nZFAAC2MTREFQk092.png-wh_500x0-wm_3 -wmp_4-s_3524330545.png "title=" image 3.png "alt=" Wkiom1ftgk2a0nzfaac2mtrefqk092.png-wh_50 "/>

2.

User uid and gid can be specified at the same time

Useradd-u 888-g 888 Test

3.

Add user instructions (to delete test before it can be established)

Useradd-c "Test User" test

4.

Specify User home Directory

useradd-d/mnt/test Test

5.

Specify the shell type used by the user

Useradd test-s/bin/tcsh

6.

See the types of shells

&nbsp123&nbsp123

&nbsp123

650) this.width=650; "Src=" Http://s5.51cto.com/wyfs02/M01/88/45/wKioL1ftGLqxGpG2AACwMc2OJ08198.png-wh_500x0-wm_3 -wmp_4-s_414170767.png "title=" image 4.png "alt=" Wkiol1ftglqxgpg2aacwmc2oj08198.png-wh_50 "/>

&nbsp123

&nbsp123

&nbsp123&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

&nbsp123

Linux Learning Note Four