How to create a user in Linux

For general users, the home directory is the only place on the hard disk where the original data can be written. The common path name is/home/login_user_name.

The main directory is used to store various user files: Setting files, program configuration files, user documents, data Netscape cache, emails, and so on. As a common user, you can create a new directory under the main directory to arrange your own directory structure. Other users cannot read your files or write data to your home directory unless you grant them proper permissions.

In addition to files in your home directory, you can also view, read, and execute many files in the system, but generally they cannot modify or delete these files.

A root user (also called a Super User) is a special system management account that can modify any file in the system. It is not a good habit to use the root user as the default logon user-Your misoperation may cause serious consequences. We recommend that you set a general account for your daily use. You can log on to the root user mode only when you need to use the root user permission. Generally, the root user is the only user after Linux Initialization and installation.

Use the root user to create a common user:

Adduser Joe
Passwd Joe
[Enter the User Password]
[Re-enter the user password for confirmation]

In the preceding example, the Super User Root is required. The above command generates a user named Joe in the system, and then sets the password of the user. Now, you can tell Joe his username and initial password. Then he can log on to the system and change his password. Note that both the user name and password are case sensitive.

A super user can change anyone's password even though he/she cannot read the user's password. The User Password adopts a one-way encryption algorithm. After encryption, only the encrypted password is stored on the system. For old systems, the password is usually stored in the/etc/passwd file, new systems generally exist in/etc/shadow files, and unencrypted password files are never stored in the system. When a user logs on, the system compares the result obtained by using the same encryption algorithm as the user's input password with the result in the password file (/etc/passwd or/etc/shadow.

The separation of superusers and general users makes the Linux system more secure-and even makes it difficult for viruses to make a difference in the Linux system (because the user's program can only write data to his/her own in a directory with read/write permissions, will not infect the core part of the entire operating system ).

It is generally recommended that you change your password immediately when logging on to the system for the first time:

Passwd
Changing password for Joe
(Current) Unix Password: [enter the old password]
New Password: [enter a new password]
Retype new password: [Repeat the new password]
Passwd: All authentication tokens updated successfully. passwd

In fact, when you enter the password, the keyboard input is not displayed on the screen for security reasons. If you change the password for the first time, you may not be able to see the keyboard input result.

In Linux, the same password can be used:

· Log on to the text Terminal
· Log on to the graphic user interface (gnome or KDE)
· Unlock the text Terminal
· Cancel Screen Protection (gnome or KDE) on the graphic user interface for password protection)