TAILIEUCHUNG - Module Linux essentials - Module 14: Managing users and groups

Module Linux essentials - Module 14 introduce managing users and groups. After studying this chapter students should be able to: Creating users and groups, understanding user and group commands, creating user IDs. | Module 14 Managing Users and Groups Exam Objective Creating Users and Groups Objective Summary Understanding user and group commands Creating User IDs Working with Groups Creating a Group The most common reason to create a group is to provide a way for users to share files. After creating or modifying a group, you can verify the changes by viewing the /etc/group file or running the getent command. The groupadd Command The groupadd command creates a new group. The -g option can be used to specify a group id: groupadd -g 506 research If the -g option is not provided, the groupadd command will automatically provide a GID for the new group. Group ID Considerations Avoid creating GIDs in the same numeric ranges where you expect to create user IDs if your system uses UPG. Recall that GIDs of under 500 are reserved for system use. The -r option will assign the new group a GID that will be less than the lowest standard UID. Group Naming Considerations The first character of the name should be either an underscore (_) or a lower-case alphabetic character (a-z). Up to 32 characters are allowed on most Linux distributions, but using more than 16 can be problematic as some distributions may not accept more than 16. After the first character, the remaining characters can be alphanumeric, dash (-) and underscore(_). The last character should not be a hyphen (-). Modifying a Group The groupmod –n command changes a group’s name. The groupmod –g command changes a group’s ID. If you change the GID for a group, then all files that were associated with that group will no longer be associated with that group. These are called “orphaned” files. To find “orphaned” files: find / -nogroup Deleting a Group Delete a group with the groupdel command. This may result in “orphaned” files. Only supplemental groups can be deleted. Working with Users The /etc/default/useradd File The /etc/default/useradd file is used to define default settings when creating user accounts. Default settings can .

• Hệ điều hành
• Linux essentials
• Module Linux essentials
• Managing users
• Managing groups
• Account information
• Password security
• Linux essentials chapters
• Using Linux
• Command line skills
• Network configuration
• History of Linux
• Linux system
• Open source
• Linux runs
• Desktop skills
• Working in Linux
• Command line
• Red Hat Linux Essentials
• Linux Ideas and History
• Linux Usage Basics
• Running Commands
• Browsing the Filesystem
• Linux command line
• Basic shell
• Command line interface
• Major open source applications
• Mobile applications
• Web servers
• Mail servers
• The man command
• Controlling the man page display
• Man page sections
• Working with files
• Working with directories
• Directory path
• Home directory
• The command line
• Archiving file
• Decompressed file
• Lossy compression
• Searching data from files
• Extracting data from files
• Command line pipes
• Redirecting STDOUT
• Basic scripting
• Turning commands into a script
• Basic text editing
• Basic shell scripting
• Understanding computer hardware
• System Information
• Viewing CPU information
• Peripheral devices
• Managing packages
• Managing processes
• Debian package management
• RPM based management
• Domain Name Service
• IP addressing
• Configuring the network
• System security
• User security
• System users
• Identifying user types
• Managing file permissions
• Identity information
• Chmod command
• Umask command
• Special permissions
• Setuid permission
• Setgid permission
• Working with sticky bit
• Slackware Linux Essentials
• 2nd Edition
• Second Edition
• JavaScript
• Enlightenment
• JavaScript 1
• Mobile Cookbook
• windows operating system
• unix operating system
• system administration
• installation tips
• operating system
• linux
• Managing Linux Systems
• TCP IP essentials
• A Lab Based approach
• TCP IP overview
• Linux and TCP IP networking
• A single segment network
• The Cisco IOS
• Dynamic routing
• system administrators
• mac operating system
• installation experience
• linux operating system
• computer software
• computer tips
• It