命令linux用户管理命令(添加,删除,修改)（Linux user management commands (add, delete, modify)）

linux用户管理命令(添加,删除,修改) Linux user managementcommands (add, del et e, modi fy) 

Linux forced landing users kicked off

View users landing in machines

[root@sunsyk w~]#

16:29:02 up 2 days, 2:35, 5 users, load average: 0.03, 0.05,

0.01

USER, TTY, FROM, LOGIN@, IDLE, JCPU, PCPU, WHAT

Root pts/1 : 0, Tue15, 2days, 1:44, 0.04s, -bash

Root pts/2: 0, Tue15, 46:42m, 0.05s, 0.05s, Bash

Root pts/3: 0, Tue15, 2days, 0.02s, 0.02s, Bash

Root, pts/4, 172.20.52. 114, 14: 17, 58:48, 0. 16s, 0.03s,sqlplus

Root, pts/5, 172.20.52. 114, 15:31, 0.00s, 0.03s, 0.00s, wI put the pts/1 out (only root to kick off the user)[root@sunsyk pkill -kill -t pts/1 ~]#

[root@sunsyk pkill -kill -t pts/2 ~]#

[root@sunsyk pkill -kill -t pts/3 ~]#

See is not kicked off

[root@sunsyk w~]#

16:34:16 up 2 days, 2:40, 2 users, load average: 0, 0.05, 0.02USER, TTY, FROM, LOGIN@, IDLE, JCPU, PCPU, WHAT

Root, pts/4, 172.20.52. 114, 14: 17, 1 :04m, 0. 16s, 0.03s,sqlplus

Root, pts/5, 172.20.52. 114, 15:31, 0.00s, 0.03s, 0.00s, wLog in as the login command:

During the user login system, you can also change the identitywith the "login" command and even log on to other hosts inaddition to the "Su-" command. If you use the "login" commandto change the identity, as long as the input will change theusername directly in the command: [root@ns1 root]# loginCaroline - > change user name is Caroline, if you want to logon the other host, need to use the "-h"parameter to the "login"command: [root@ns1 root]# login-h linux2 - >Linux2 login forthe host.

Log in as the rlogin command:

Inaddition to using the login command, rlogin can alsobe usedto log on to remote hosts, and its usage is simple. Here is an

example of a connection to linux2. jschouse.com:

[root@ns1 root]# rlogin linux2. jschouse.com - >linux2. jschouse. com login

Password: is in the same name - > * login default, so there isno "login" informat ion

Login incorrect- > if the name used to login with the username,can directly press the "Enter", and ignore the errori nformat ion

Login: Jack - > to enter a different username

Password: * - > password

The use of /etc/nologin files:

If you want to only root can log on the host, other account cannot log in, you can add a file named "nologin" in the /etcdirectory in the file, as long as the random input characterscan be found in the file system as long as there will preventother users login.

System logout:

The front is introduced to change the identity in the "login"command, and can log on the other host, and login relative tothe command "logout", it can make the currently logged on userlog off the system, so that other users login. The use of thiscommand is simple. You can log on to the system as long as you

enter "logout": [root@ns1 root]# logout

As described earlier, the Linux system is a multi-useroperating system, and each user' s access to the system needsto be set by the system administrator. This section describessome of the commands that the system administrator manages forusers and user groups.

4.6. 1 creates new users

The useradd command (also using addUser) is used to create anew user account with the following commands:

Table 4 - 19 useradd command common options

Common phenomenon

Significance

-d

Sets the landing directory for new users

-e

Set the new user' s stop date, the date format is MM/DD/YY-f

A few days after the account has expired permanent suspension.The value is 0 when the account is immediately stopped. When

duty is -1, this function is turned off. The default value is-1

-g

Enable new users to join groups

-G

Add new users to a new group. Each group is separated by commas,which must not be enclosed in blank words

-s

Specifies the login Shell for the new user

-u

Sets the ID value for new users

When a new user is created successfully, a line of informationabout that user is added to the /etc/passwd file, formatted asfollows:

[user name: [password] : [UID] : [GID] : [identity description] :[home directory] [landing Shell]

One of the fields is divided into 7 parts by the colon ":".Because less than 500 of the UID and GID are generally the systemitself retained, do not do ordinary users and groups of signs,

so the new increase in users and groups are generally UID andGID greater than 500.

For example, use the following command:

Root@localhost root useradd user1 #

A user named userl will be created, and the user managementcommand has been introduced, and no more is introduced here.The result of executing the useradd command is shown in figure11-13.

4.6.2 sets and modifies user password passwd

The passwd command is used to set and modify user commands. Onlysuper users and users can change their passwords themselves,and other ordinary users do not have the right to modify otheruser passwords. Its order is as follows:

# passwd username.

To avoid entering passwords, it is noticed howmany bits, Linuxdoes not use a password like Windows echo [shown as *] , so theinput of these characters is invisible. For example, to setpasswords for new userl users, use the following command:Root@localhost root passwd user1 #

According to the system prompted information, enter thepassword two times, the system will display:

Passwd: : all, authentication, tokens, updated, successfullyIndicates that the change password succeeded. The new user' sjob is completed only after the user has set the password,otherwise the user name cannot be used to log on.

4.6. 3 modify user information usermod

The usermod command is used to modify user information, and itscommand format is as follows:

# usermod option: user name.

The common command option, 11-20, is shown.

Table 4-20 common options for usermod commands

Common options

Significance

-d

Update the user' s new login directory

-e

Set the new user' s stop date, the date format is MM/DD/YY-f

A few days after the account has expired permanent suspension.The value is 0 when the account is immediately stopped. Whenduty is -1, this function is turned off. The default value is-1

-g

Update user new user to join group

-G

Define the user as a group of groups members. Each group uses"?"" Separate from blank words

-l

To change the name of the user login, the user at the same timethe directory name will follow the change into a new name-s

Specify a new user Shell

-u

The user ID value must be the unique ID value. The user directorytree document directory the userID will automatically changeon the support directory document is to manually changeFor example, the following command modif ies user information:

Root@localhost root usermod- d/home/user2 s/bin/bash user2 -#

Set the home directory path for user name user2 at/home/user1,and the Shell setting for login to /usr/bin/gcc.

In general, the usermod command modifies user accountinformation with reference to the commands section. However,usermod does not allow changing the user account name on theline, so when using usermod to change user account information,You must verify that this name has not been executed on thec omputer.

4.6.4 new group groupadd

The groupadd command is used to create a new group of users,and the commands are as follows:

# groupadd options: user name.

Common options are:

-g:GID value. Unless the -o parameter is used, the value mustbe unique, not the same, and the value must not be negative.The GID value is preset to be minimum, not less than 500 andincreased sequentially. 0 - 499 is traditionally reserved forsystem account usage.