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This article mainly explains "how to view users and user groups in linux". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "how to view users and user groups in linux".

Whois

Function description: find and display user information.

Grammar: whois [account name]

Additional note: the whois instruction will find and display the user-related information of the specified account, because it is to look up the WHOIS database of Network Solutions, so the account name must be registered above to be found, and there is no case difference in the name.

Whoami

Function description: first it seems that the user name.

Grammar: whoami [--help] [--version]

Supplementary note: displays its own user name, and this instruction is equivalent to the execution of the "id-un" instruction.

Parameters:

-- help online help.

-- version displays version information.

Who

Function description: displays the user information currently logged in to the system.

Grammar: who [- Himqsw] [--help] [--version] [am I] [record file]

Additional note: execute this instruction to know which users are currently logged in to the system. Executing the who instruction alone will list the login account, the terminal used, the login time and where you are logged in or which X monitor you are using.

Parameters:

-H or-- heading displays the header information column of each field.

-I or-u or-- idle shows idle time, and if the user takes any action within the previous minute, it will be marked "." If the user has not taken any action for more than 24 hours, the string "old" is marked.

-m this parameter has the same effect as the specified "am I" string.

-Q or-- count displays only the account name and total number of people logged in to the system.

-s this parameter will be ignored and will not be processed, and will only be responsible for solving the compatibility problem of other versions of the who directive.

-w or-T or-- mesg or-- message or-- writable displays the user's information status bar.

-- help online help.

-- version displays version information.

W

Function description: displays the user information currently logged in to the system.

Grammar: W [- fhlsuV] [user name]

Add: by executing this instruction, you can know who are currently logged in to the system and the programs they are executing. Execute w separately

The directive displays all users, or you can specify a user name to display only information about a user.

Parameters:

-f turns on or off showing where the user logs in to the system.

-h does not display the title information column of each field.

-l uses a detailed format list, which is the default value.

-s uses a concise format list and does not show the login time of the user, the CPU time spent by the terminal phase jobs and programs.

-u ignores the name of the executing program and the information that the program takes CPU time.

-V displays version information.

Finger command

The function of the finger command is to query the user's information, which usually displays the user name, home directory, stagnation time, login time, login shell and other information of a user in the system. If you want to query user information on a remote machine, you need to follow the user name with "@ hostname" in the format of [username @ hostname], but the network host you want to query needs to run the finger daemon.

The general format of the command is:

Finger [option] [user] [user @ host]

The options in the command have the following meanings:

-s displays the user's registration name, actual name, terminal name, write status, stagnation time, login time and other information.

In addition to the information displayed with the-s option, it also displays information such as the user's home directory, login shell, mail status, and the contents of .plan, .project, and .forward files under the user's home directory.

-p is the same as the-l option except that the .plan file and .project file are not displayed.

Use the finger command on the local machine.

$finger xxq

Login: xxq Name:

Directory: / home/xxq Shell: / bin/bash

Last login Thu Jan 1 21:43 (CST) on tty1

No mail.

No Plan.

$finger

Login Name Tty Idle Login Time Office Office Phone

Root root * 1 28 Nov 25 09:17

……

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The / etc/group file contains all groups

All usernames that exist on / etc/shadow and / etc/passwd systems

The method of modifying the group to which the current user belongs

Usermod or you can modify the / etc/paaawd file directly.

Vlock (virtual console lock)

Function description: lock the virtual terminal.

Grammar: vlock [- achv]

Additional note: execute the vlock instruction to lock the virtual terminal and avoid others from using it.

Parameters:

-an or-- all locks all terminal phase jobs, and if you use this parameter in a full-screen terminal, you will use the keyboard

The function of switching terminals is also turned off.

-c or-- current locks the current terminal phase job, which is the default value.

-h or-- help online help.

-v or-- version displays version information.

Usermod

Function description: modify user account.

Grammar: usermod [- LU] [- c] [- d] [- e] [- f] [- g] [- G] [- l] [- s] [- u] [user account]

Note: usermod can be used to modify the settings of a user's account.

Parameters:

-c modify the remarks of the user account.

-d login directory > modify the directory when the user logs in.

-e modify the validity period of the account.

-f modify how many days after the password expires to close the account.

-g modify the group to which the user belongs.

-G modifies the additional group to which the user belongs.

-l modify the user account name.

-L locks the user's password, invalidating it.

-s modifies the shell used by the user after login.

-u modify user ID.

-U unlocks the password.

Userdel

Function description: delete user account.

Syntax: userdel [- r] [user account]

Supplementary note: userdel can delete user accounts and related files. If no parameters are added, only the user account will be deleted, not the related files.

Parameters:

-f Delete the user login directory and all files in the directory.

Userconf

Function description: user account setting program.

Grammar: userconf [--addgroup] [--adduser] [--delgroup] [--deluser] [--help]

Supplementary note: userconf is actually the symbolic connection of linuxconf, providing a graphical interface for administrators to establish and manage all kinds of accounts. If you do not add any parameters, you will enter the graphical interface.

Parameters:

-- A new group is added to addgroup.

-- add a user account to adduser.

-- delgroup deletes the group.

-- deluser deletes user accounts.

-- help displays help.

Useradd

Function description: set up user account.

Grammar: useradd [- mMnr] [- c] [- d] [- e] [- f] [- g] [- G] [- s] [- u] [user account] or useradd-D [- b] [- e] [- f] [- g] [- G] [- s]

Note: useradd can be used to set up user accounts. After the account is set up, use passwd to set the password of the account. You can use userdel to delete the account. The account created using the useradd directive is actually saved in the / etc/passwd text file.

Parameters:

-c plus remarks. The remarks text is saved in the comments field of passwd.

-d specifies the starting directory when the user logs in.

-D change the default value.

-e specifies the validity period of the account.

-f specifies how many days after the password expires, the account will be closed.

-g specifies the group to which the user belongs.

-G specifies the additional group to which the user belongs.

-m automatically sets up the login directory of the user.

-M do not automatically create a user's login directory.

-n cancels the creation of a group with the user name.

-r set up a system account.

-s specifies the shell that the user will use after logging in.

-u specifies the user ID.

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