Module 03 - Administrative Tasks

Chapter 1-Living in a Network Centric WorldObjectives
Objective 1: Manage User and Group Accounts and Related System Files
Objective 2: Automate System Administration Tasks by Scheduling Jobs
Objective 3: Localization and Internationalization
LPI Linux Certification http://www.bkacad.com
Manage User and Group Accounts and Related System Files
Managing user accounts is an important aspect of running a Linux system
User Accounts and the Password File
When a new user account is added to a Linux system, an entry is added to a list of users in the password file, which is stored in /etc/passwd
The password file is in plain text and is readable by everyone on the system.
Each line in the password file contains information:
Groups and the Group File
Groups are defined in the file /etc/group
Like the passwd file, the group file contains colon-separated fields:
Group name: Each group must have a unique name
Group password
Group member list: list of group members by username
The Shadow Password and Shadow Group Systems
Encrypted passwords must be secure from all users on the system
To do this, the encrypted password is moved to a new file that shadows the password file line for line ( /etc/shadow )
loginID:password:lastchg:min:max:warn:inactive:expire:
The first two fields contain the username and the encrypted passwords. The remaining fields contain optional additional information on password aging information.
Group passwords and shadow groups
Just as user accounts listed in /etc/passwd are protected by encrypted passwords,groups listed in /etc/group can also be protected by passwords
A group password can be used to allow access to a group by a user account that is not actually a member of the group
To protect against such attacks, passwords in /etc/group can be shadowed.
The protected passwords are stored in /etc/gshadow
User and Group Management Commands
useradd
useradd
Using cron
The cron facility consists of two programs:
Crond: This is the cron daemon, which is the process that executes your instructions
Crontab: This is the cron table manipulation program
The cron daemon wakes up every minute and examines all crontab files, executing any commands scheduled for that time.
Using cron
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Using at
Execution of commands on a regular, periodic schedule
The at facility accepts commands from standard input or from a file.
[root@bkad-lpi-01 ~]# at 9:57am
[root@bkad-lpi-01 ~]#
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Using at
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Objective 3: Localization and Internationalization
Internationalization is the process of designing a software application so that it can be adapted to various languages and regions without engineering changes.

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Module 03 - Administrative Tasks