Title: Basic Administration
1Chapter 8
- Basic Administration
- Tasks
2Objectives
- In this chapter, you will
- Create and manage Linux user accounts
- Install and maintain types of Linux systems
- Manage processes on Linux using basic commands
3Managing User Accounts
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- To complete any operation in Linux, a person must
first log in using a valid user account name and
password - Setting up and maintaining these user accounts is
an important part of the work of a system
administrator
4Types of User Accounts
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- Types of user accounts include
- root account
- Regular accounts
- Special accounts
5The root Account
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- The administrative account (the superuser) on a
Linux system is named root - The root user can perform any operation on a
Linux system - The su utility (for substitute user) temporarily
changes your access rights to those of another
user
6Regular Users
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- Regular user accounts are for users who log in at
a keyboard and use the Linux system - Regular user account names typically use a
combination of first name or initial and last
name or initial
7Special Users
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- Special accounts cannot be used to log in
- Special accounts are used by programs running on
Linux
8Linux Groups
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- A group is a collection of user accounts that can
be collectively granted access to files and
directories - A user can be a member of multiple groups, but
can only have one primary group - A User Private Group system creates a group with
a single member for each new user account
9A User as a Member of Multiple Groups
10User and Group Files
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- User account information is stored in the file
/etc/passwd - To edit the /etc/passwd file, use the special
editing program vipw - Groups on a Linux system are defined in
/etc/group - To edit the /etc/group file, use the command vigr
11Shadow Passwords
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- Encrypted passwords are stored in /etc/shadow
- Regular users cannot read encrypted passwords
- Shadow Password Suite is a collection of
password-related programs that have been modified
to recognize the /etc/shadow file
12Creating New User Accounts
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- New user accounts can be created
- With the useradd command
- With various graphical utilities
- Default settings apply when using the useradd
command alone - Default settings can be modified on the command
line or by editing a configuration file for
useradd
13Configuring Users Graphically in Red Hat Linux 7.3
14useradd Command Options
15Changing User Passwords
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- A password is not defined by useradd when a new
user account is created - The passwd command is used to define or change a
users password - You must enter the new password twice
16Creating New Groups
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- To create a new group, use the groupadd command
- To add a new group, include the group name as a
parameter
17Modifying User and Group Accounts
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- The usermod command allows you to modify user
account parameters stored in /etc/passwd or
/etc/shadow - The groupmod command lets you modify membership
of a group
18Automating Home Directory Creation
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- Files contained in /etc/skel are automatically
copied into each users home directory at the
time you create the account - You should place files in /etc/skel when you
first install Linux
19Disabling User Accounts
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- You can temporarily or permanently disable a user
account - Accounts can be deleted using the userdel command
- To temporarily disable a users account, change
the password with the passwd command
20Maintaining File Systems
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- File system refers to an organized set of data
that can be accessed via the standard Linux
directory structure - To access a file system in Linux, it must first
be mounted into the root directory structure - A mount point is the path in the directory
structure where you access the data in a file
system - Use the mount command to make a new file system
accessible via a mount point
21Automatically Mounted File Systems
22File Systems Mounted in a Linux Directory
Structure
23Checking File System Status
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- The df command displays space usage information
for each file system that is currently mounted - The du utility lists the size of a directory and
all its subdirectories - You can use various graphical tools and system
administration scripts to check the status of
file systems
24Creating New File Systems
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- You can install new file systems that are
permanent or temporary - File systems can be stored on a device with
removable media or fixed media - Once the hard disk or other device is installed,
you can use the Linux fdisk command to examine
its partitions, creating new Linux partitions
25Using the fdisk Utility
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- To manage partitions in Linux after the operating
system is installed, use the fdisk utility - The fdisk utility can configure partition data on
a hard disk - Your modifications to the partition table are
only effective when you write the changes to disk
with the w command to exit fdisk
26fdisk Commands
27Sample Output of the p Command in fdisk
28Formatting File Systems
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- File system journaling is a feature that protects
against data corruption by tracking each write
to the hard disk in a special way so that it will
either be completely finished or left completely
undone - New partitions must be formatted using mke2fs or
mkswap before they can be used
29Mounting File Systems
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- After you have formatted a file system, you can
mount it - To access a file system, you use the mount
command - The floppy disk drive and CD-ROM drive are
mounted to /mnt/floppy and /mnt/cdrom
30Unmounting File Systems
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- To unmount a file system, use the umount command
with the device name or mount point - A file system cannot be in use when you unmount it
31Automating File System Mounting
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- The new file systems that you create from
additional hard disks or other devices can also
be automatically mounted at boot time - The key to automounting file systems is the
/etc/fstab configuration file which contains one
line for each file system that you want to have
automounted when Linux boots
32Option Field Settings for the mount Command
33Managing Swap Space
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- The swap space is a special partition type used
by the Linux kernel for virtual memory - You can use the mkswap command to format a swap
partition - Swap space is activated by the swapon command
within the system initialization scripts - The vmstat command displays current status
details for how virtual memory is being used
34Setting Quotas on Disk Usage
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- Limits on the amount of hard disk space that any
user or group can use are called disk quotas - Use the edquota command to establish a quota for
one or more users or groups - Activate the quota system using the quotaon
command
35Simple Task Management
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- To control processes running on Linux, you can
use the following - The ps command
- The bg command
- The fg command
36Job Control in the Shell
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- When you start a program, that program takes
control of the command line where you are working - The jobs command lists all jobs or processes that
are running from the current shell - The fg command places processes in the foreground
- The bg command places processes in the background
command
37Using Virtual Consoles
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- A virtual console is a separate login screen that
you access by pressing a combination of keys on
your keyboard - A virtual console allows you to start multiple
text-based login sessions on the same computer - The virtual consoles are assigned to the function
keys
38Learning about Processes
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- A simple ps command shows you only the commands
that you have started in the current
command-line environment - Multiple processes can be started from a single
shell
39Controlling Processes
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- The kill command is used to kill, or end,
processes - Signals are messages that can be sent between
processes - The killall command sends a signal to all
processes started by a given command
40Summary
- Types of user accounts include root, regular
accounts, and special accounts - New user accounts can be created with the useradd
command or with various graphical utilities - New groups can be created with the groupadd
command - File systems are accessed by using the mount
command to specify a device and a mount point - The df and du commands display status and size
information about file systems
41Summary
- The fdisk utility can configure partition data on
a hard disk. - The vmstat command displays how virtual memory is
being used - Within a shell, the jobs command manages these
processes, placing them in the foreground or
background - Virtual consoles let you log in at multiple
independent text-mode screens - The kill command sends signals to processes or to
the Linux kernel when necessary to end a process