UNIX System administration: Creating and managing user accounts

To complete this chapter, you can do the following things:

To list the steps to establish a user account

Understand the meaning of each field in the passwd file

Understand the meaning of each field in the/etc/group file

Create, modify, and delete user accounts

Enable and disable a user account

1.1 User and user groups-using system resources and data

In order to use the system resources, the user first must login the system, http://www.aliyun.com/zixun/aggregation/13879.html "> system administrator may control other user to log in the system, may prevent the unauthorized user to run the program, consumes the system resources , you can also control the access of others to the data stored in the system.

Users in the system are divided into one or more user groups. A typical scenario is that a file can be accessed by a user of a group, but not by users outside of the user group. User access to files and directories is based on the definition of the group to which he belongs.

You assign a user name (or login name) to each user who uses your system, as well as select a group and decide which user is assigned to which group.

Users can use command/usr/bin/id to check their user IDs and the group IDs they belong to.

1.2 User account Definition

Users who want to log on to a system must have a valid username, user ID number, password, and other account information defined in passwd. By modifying file/etc/group, users can belong to other groups. Finally, most of the filesystem directories have a directory where they can store their own files and directories.

You can use the command line Useradd,userdel, and Usermod or the VI Editor to manage the user's account number.