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Linux+ Guide to Linux Certification, Third Edition. Chapter 10 Common Administrative Tasks. Objectives. Set up, manage, and print to printers on a Linux system Understand the purpose of log files and how they are administered Create, modify, manage, and delete user and group accounts.

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Linux guide to linux certification third edition

Linux+ Guide to Linux Certification, Third Edition

Chapter 10

Common Administrative Tasks


Objectives
Objectives

  • Set up, manage, and print to printers on a Linux system

  • Understand the purpose of log files and how they are administered

  • Create, modify, manage, and delete user and group accounts

Linux+ Guide to Linux Certification, 3e


Printer administration the common unix printing system
Printer Administration: The Common UNIX Printing System

  • Common Unix Printing System (CUPS): most common printing system used on Linux

  • Print job: set of information sent to a printer at the same time

    • Can consist of a file, a set of files, or the output of a command

  • lp command: sends a print job to a printer

Linux+ Guide to Linux Certification, 3e


Printer administration the common unix printing system continued
Printer Administration: The Common UNIX Printing System (continued)

  • cups daemon (cupsd): responsible for printing in CUPS printing system

  • Print job ID: print job’s unique identifier

    • Assigned by cupsd

  • Print queue: directory holding print jobs waiting to be printed

    • Typically /var/spool/cups

Linux+ Guide to Linux Certification, 3e


Printer administration the common unix printing system continued1
Printer Administration: The Common UNIX Printing System (continued)

  • Printer can accept or reject request to print

    • If rejected, CUPS gives an error message

  • Spooling or queuing: accepting print jobs into a print queue

  • Printing: sending print jobs from print queue to a printer

    • Occurs if the printer is enabled, cupsd removes copy of print job from the print queue.

Linux+ Guide to Linux Certification, 3e


Printer administration the common unix printing system continued2
Printer Administration: The Common UNIX Printing System (continued)

Figure 10-1: The print process

Linux+ Guide to Linux Certification, 3e


Printer administration the common unix printing system continued3
Printer Administration: The Common UNIX Printing System (continued)

  • lpstat command: with –t (total) option, lists all printers and their status

  • cupsaccept, cupsreject, cupsenable, and cupsdisable commands: manipulate status of a printer

    • -r option: used to specify reason for cupsdisable and cupsreject commands

Linux+ Guide to Linux Certification, 3e


Managing print jobs
Managing Print Jobs (continued)

  • lp –d command: print to a specified printer

    • If –d option omitted, prints to default printer

  • lpoptions –d command: set default printer

  • Each user can set his own default printer

    • Add name of the default printer to .lpoptions file in home directory

    • Use PRINTER or LPDEST variable

Linux+ Guide to Linux Certification, 3e


Managing print jobs continued
Managing Print Jobs (continued) (continued)

  • lp command accepts information from stdin

  • lpstat command can list print jobs in queue for a printer

  • cancel command: remove print jobs from print queue

    • Receives print job IDs as arguments

    • -u option: remove all the jobs sent by specified user

  • lpadmin command: perform printer administration

    • e.g., restrict specific user access to specific printers

Linux+ Guide to Linux Certification, 3e


Managing print jobs continued1
Managing Print Jobs (continued) (continued)

Table 10-1: Common options to the lp command

Linux+ Guide to Linux Certification, 3e


Managing print jobs continued2
Managing Print Jobs (continued) (continued)

Table 10-2: Common options to the lpstatcommand

Linux+ Guide to Linux Certification, 3e


The lpd printing system
The LPD Printing System (continued)

  • Line Printer Daemon (LPD): printing system used on older Linux systems

  • lpr command: send documents to a print queue

  • lpc command: view status of printers

  • lpq command: view print jobs in print queue

  • lprm command: remove print jobs

  • CUPS contains versions of the lpr, lpc, lpq, and lprm commands

Linux+ Guide to Linux Certification, 3e


Configuring printers
Configuring Printers (continued)

  • /etc/cups/cupsd.conf: contains cupsd settings

  • /etc/cups/printers.conf: contains each printer’s configuration information

  • Printer Configuration tool: used to edit printer and cupsd setting files and thus configure printers

    • Activated using the system-config-printer command in a desktop environment

    • e.g., add new printers

Linux+ Guide to Linux Certification, 3e


Configuring printers continued
Configuring Printers (continued) (continued)

Figure 10-2: The Printer Configuration tool

Linux+ Guide to Linux Certification, 3e


Configuring printers continued1
Configuring Printers (continued) (continued)

Figure 10-3: Specifying the printer device

Linux+ Guide to Linux Certification, 3e


Configuring printers continued2
Configuring Printers (continued) (continued)

  • For local printers that do not support PnP, must specify the Uniform Resource Identifier (URI) for the device

  • Within Printer Configuration tool you can:

    • Give a printer a name to identify it within programs and commands

    • Specify printer location and description

    • Modify printer properties

    • Manage the status of the printer, share it using IPP, choose an error action, and configure banner pages

Linux+ Guide to Linux Certification, 3e


Configuring printers continued3
Configuring Printers (continued) (continued)

Figure 10-4: Selecting the printer manufacturer

Linux+ Guide to Linux Certification, 3e


Configuring printers continued4
Configuring Printers (continued) (continued)

Figure 10-5: Selecting the printer model

Linux+ Guide to Linux Certification, 3e


Configuring printers continued5
Configuring Printers (continued) (continued)

Figure 10-6: Completing the creation of a new printer

Linux+ Guide to Linux Certification, 3e


Configuring printers continued6
Configuring Printers (continued) (continued)

Figure 10-7: Viewing installed printers

Linux+ Guide to Linux Certification, 3e


Configuring printers continued7
Configuring Printers (continued) (continued)

Figure 10-8: Modifying printer properties

Linux+ Guide to Linux Certification, 3e


Configuring printers continued8
Configuring Printers (continued) (continued)

Figure 10-9: The Policies section of printer properties

Linux+ Guide to Linux Certification, 3e


Configuring printers continued9
Configuring Printers (continued) (continued)

Figure 10-10: The Access control section of printer properties

Linux+ Guide to Linux Certification, 3e


Configuring printers continued10
Configuring Printers (continued) (continued)

  • To apply standard printer properties to several printers on a system, create printer class

    • Apply the properties to the printer class

  • Printer Configuration tool allows configuration of the properties of CUPS daemon

    • Add shared network printers

    • Share printers on the system

    • Remotely create and manage printers

Linux+ Guide to Linux Certification, 3e


Configuring printers continued11
Configuring Printers (continued) (continued)

Figure 10-11: Configuring CUPS settings

Linux+ Guide to Linux Certification, 3e


Log file administration
Log File Administration (continued)

  • Log file: file containing system information

    • Typically recorded during daemon activity

    • Information includes error messages

  • /var/log: contains most log files

    • Many programs store log files in subdirectories

Linux+ Guide to Linux Certification, 3e


Log file administration continued
Log File Administration (continued) (continued)

Table 10-3: Common Linux log files found in /var/log

Linux+ Guide to Linux Certification, 3e


The system log daemon
The System Log Daemon (continued)

  • System log daemon (syslogd): central handling of logging system events

    • Creates /dev/log socket for system processes to write to

    • Writes to appropriate log file using /etc/rsyslog.conf file

      • Entries indicate facility and priority

  • Facility: area of system that information is gathered from

  • Priority: importance of system information

Linux+ Guide to Linux Certification, 3e


The system log daemon continued
The System Log Daemon (continued) (continued)

Table 10-4: Facilities used by the System Log Daemon

Linux+ Guide to Linux Certification, 3e


The system log daemon continued1
The System Log Daemon (continued) (continued)

Table 10-5: Priorities used by the log daemon

Linux+ Guide to Linux Certification, 3e


Managing log files
Managing Log Files (continued)

  • Log files can take up unnecessary space

    • Clear contents occasionally

      • Print copy for records

      • Use > redirection symbol to clear log file

      • Use cron daemon for repetitive clearing

  • Do not remove log files

    • Permissions and ownership will be removed

Linux+ Guide to Linux Certification, 3e


Managing log files continued
Managing Log Files (continued) (continued)

  • logrotate command: back up and clear log files

    • Compress old log files and save under new name

  • /etc/logrotate.conf: used by logrotate utility

    • Specifies rotation parameters for log files

Linux+ Guide to Linux Certification, 3e


Administering users and groups
Administering Users and Groups (continued)

  • Authentication: verify user’s identity

    • Compare username and password to system database

  • Database containing user account information typically consists of two files

    • /etc/passwd: user account information

    • /etc/shadow: encrypted password and expiration information

  • pwconv command: convert system to use an /etc/shadow file for encrypted password storage

Linux+ Guide to Linux Certification, 3e


Administering users and groups continued
Administering Users and Groups (continued) (continued)

  • pwunconv command: revert back to using an /etc/passwd file only

  • User Identifier (UID): unique user ID for each user

  • Group Identifier (GID): primary group ID for each user

  • Primary group: group owner for all files created by a user

  • General Electric Comprehensive Operating System (GECOS): text description of the user

    • Typically left blank

Linux+ Guide to Linux Certification, 3e


Administering users and groups continued1
Administering Users and Groups (continued) (continued)

  • Root user usually listed at top of /etc/passwd file

    • Next are listed system daemons

  • Password field differs in the two files:

    • /etc/shadow: contains encrypted password

    • /etc/passwd: contains an x character

  • lastchange: date of most recent password change

    • Number represents number of days since January 1, 1970

Linux+ Guide to Linux Certification, 3e


Administering users and groups continued2
Administering Users and Groups (continued) (continued)

  • Passwords often set to expire at certain intervals

    • Intervals specified in /etc/shadow

      • Minimum number of days before changing password

      • Maximum number of days to use password

      • Number of days before password expiration in which user is warned to change password

  • /etc/group file: Lists all groups and their members

    • Allows users to belong to multiple groups

    • Password field usually contains an x

Linux+ Guide to Linux Certification, 3e


Creating user accounts
Creating User Accounts (continued)

  • useradd command: add new user accounts

  • Most new user information comes from two files

    • /etc/login.defs

      • E-mail location, password expiration, minimum password length, range of UIDs and GIDs

    • /etc/default/useradd

      • Default primary group, home directory location, password expiration info, shell, skeleton directory

Linux+ Guide to Linux Certification, 3e


Creating user accounts continued
Creating User Accounts (continued) (continued)

  • Skeleton directory: contains environment files to copy to new users’ home directories

    • Usually /etc/skel

  • Override default parameters by specifying options to useradd command

  • passwd command: set a user’s password

    • If no arguments, sets current user’s password

    • User accounts must have password set to log on

    • Root user can change any user’s password

Linux+ Guide to Linux Certification, 3e


Creating user accounts continued1
Creating User Accounts (continued) (continued)

Table 10-6: Common options to the useradd command

Linux+ Guide to Linux Certification, 3e


Modifying user accounts
Modifying User Accounts (continued)

  • usermod command: modify user account information

  • chage command: modify password expiration information

  • Locking an account: make an account temporarily unusable

    • Alter password information

    • Use –l or –L options of passwd command

    • chsh command: change a valid shell to an invalid shell

Linux+ Guide to Linux Certification, 3e


Modifying user accounts continued
Modifying User Accounts (continued) (continued)

Table 10-7: Common options to the usermod command

Linux+ Guide to Linux Certification, 3e


Deleting user accounts
Deleting User Accounts (continued)

  • userdel command: remove user accounts

    • Specify user name as argument

  • When an account is deleted, files previously owned by the user become owned by a number representing UID of deleted user

    • Next user with that UID will own the files

Linux+ Guide to Linux Certification, 3e


Managing groups
Managing Groups (continued)

  • Can add groups by editing /etc/group file

  • groupadd command: add a group to the system

  • groupmod command: modify GID name of a group on the system

  • groupdel command: remove a group from the system

Linux+ Guide to Linux Certification, 3e


Managing groups continued
Managing Groups (continued) (continued)

  • groups command: list groups that user belongs to

  • id command: list GIDs of groups that a user belongs to

  • newgrp command: temporarily change user’s primary group

  • Graphical utilities exist to create, modify, and delete user and group accounts

Linux+ Guide to Linux Certification, 3e


Managing groups continued1
Managing Groups (continued) (continued)

Figure 10-13: Configuring users and groups within a desktop environment

Linux+ Guide to Linux Certification, 3e


Summary
Summary (continued)

  • Print jobs are spooled to a print queue before being printed to a printer

  • You can configure spooling or printing by using the cupsaccept, cupsreject, cupsenable, and cupsdisable commands

  • Print jobs are created using lp, can be viewed in the queue using lpstat, and are removed from the queue using cancel

Linux+ Guide to Linux Certification, 3e


Summary continued
Summary (continued) (continued)

  • Create local and remote printers using Printer Configuration tool or by modifying /etc/cups/printers.conf

  • Most log files in Linux are stored in /var/log

  • System events are typically logged to files by the System Log Daemon

  • Log files should be cleared or rotated over time to save disk space

  • User and group account information is typically in /etc/passwd, /etc/shadow, and /etc/group

Linux+ Guide to Linux Certification, 3e


Summary continued1
Summary (continued) (continued)

  • Use the useradd command to create users and the groupadd command to create groups

  • All users must have a valid password before logging in to a Linux system

  • Users can be modified with usermod, chage, chfn, chsh, and passwd commands, and groups can be modified using groupmod command

  • The userdel and groupdel commands remove users and groups from the system, respectively

Linux+ Guide to Linux Certification, 3e


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