1. Linux+ Guide to Linux Certification, Second Edition
Chapter 11
Common Administrative Tasks

2. Linux+ Guide to Linux Certification, 2e
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 using command-line and graphical utilities
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3. 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
File, set of files, output of a command
lp command: Sends a print job to a printer
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4. 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
Print queue: Directory holding print jobs waiting to be printed
Typically /var/spool/cups
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5. 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
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6. Printer Administration: The Common UNIX Printing System (continued)
lpstat command: With –t (total) option, lists all printers and their status
accept, reject, enable, and disable commands: Manipulate status of a printer
For enable, must specify full path enable command (/usr/bin/enable)
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7. Printer Administration: The Common UNIX Printing System (continued)
Figure 11-1: The print process
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8. Linux+ Guide to Linux Certification, 2e
Managing Print Jobs
lp –d command: Print to a specified printer
If –d option omitted, prints to default printer
lpoptions –d command: Set default printer
Users can set own default printer
Add to .lpoptions file in home directory
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9. Managing Print Jobs (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
lpadmin command: Perform printer administration
e.g., restrict who can print to specific printers
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10. Managing Print Jobs (continued)
Table 11-1: Common options to the lp command
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11. Managing Print Jobs (continued)
Table 11-2: Common options to the lpstat command
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12. The LPD Printing System
Line Printer Daemon (LPD): Printing system used on older Linux systems
lpr command: Create print jobs in print queue
lpc command: View status of printers
lpq command: View print jobs in print queue
lprm command: Remove print jobs
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13. Linux+ Guide to Linux Certification, 2e
Configuring Printers
/etc/cups/cupsd.conf: Contains cupsd settings
/etc/cups/printers.conf: Contains each printer’s configuration information
Printer Configuration tool: Used to configure printers
e.g., Add new printers
Configures queue, not printer
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14. Configuring Printers (continued)
Figure 11-2: The Printer Configuration tool
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15. Configuring Printers (continued)
Figure 11-3: Specifying the name of a new printer
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16. Configuring Printers (continued)
Figure 11-5: Different queue types available for a new printer
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17. Configuring Printers (continued)
For local printers, must choose printer port
Such as /dev/lp0
For remote printers, specify name or IP address of remote server, printer name, or printer port
Enable sharing as needed
CUPS can automatically search for other shared CUPS printers
Allow remote computers to print using the LPD protocol
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18. Configuring Printers (continued)
Figure 11-6: Selecting the printer model for a new printer
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19. Configuring Printers (continued)
Figure 11-7: Completing the creation of a new printer
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20. Configuring Printers (continued)
Figure 11-8: View a configured printer
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21. Configuring Printers (continued)
Figure 11-9: Sharing a printer to network users
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22. Configuring Printers (continued)
Figure 11-10: Specifying shared printer options
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23. Log File Administration
Log file: File containing system information
/var/log: Contains most log files
Many programs store log files in subdirectories
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24. Log File Administration (continued)
Table 11-3: Common Linux log files found in /var/log
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25. Linux+ Guide to Linux Certification, 2e
The System Log Daemon
System log daemon (syslogd): Logs system events
Uses /etc/syslog.conf file
Entries indicate what information to write to what log file
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26. The System Log Daemon (continued)
Facility: Area of system that information is gathered from
Priority: Importance of system information
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27. The System Log Daemon (continued)
Table 11-4: Facilities used by the System Log Daemon
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28. The System Log Daemon (continued)
Table 11-5: Priorities used by the log daemon
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29. Linux+ Guide to Linux Certification, 2e
Managing Log Files
Log files can take up unnecessary space
Clear contents occasionally
Print copy for records
Use > redirection symbol
Do not remove log files
Permissions and ownership will be removed
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30. Managing Log Files (continued)
logrotate command: Back up and clear log files
/etc/logrotate.conf: Used by logrotate utility
Specifies rotation parameters for log files
Log files compressed after rotation
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31. Administering Users and Groups
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
Previously stored password information
/etc/shadow: Encrypted password information
pwconv command: Convert system to use an /etc/shadow file for encrypted password storage
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32. Administering Users and Groups (continued)
pwunconv command: Revert back to using an /etc/passwd file only
User Identifier (UID): Unique user ID for a user
Group Identifier (GID): Primary group ID for each user
Primary group: Group owner for all files created by a user
Specified in /etc/passwd file
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33. Administering Users and Groups (continued)
General Electric Comprehensive Operating System (GECOS): Field in /etc/passwd file containing user account description
Root user usually listed at top of /etc/passwd file
/etc/shadow: Password field contains encrypted password
/etc/passwd: Password field contains an x (not used)
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34. Administering Users and Groups (continued)
Passwords often set to expire at certain intervals
Intervals specified in /etc/shadow
/etc/group file: Lists all groups and their members
Allows users to belong to multiple groups
Password field usually contains an x
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35. Creating User Accounts
useradd command: Add new user accounts
Most new user information comes from two files:
/etc/login.defs:
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
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36. Creating User Accounts (continued)
Skeleton directory: Contains files to copy to new users’ home directories
Usually /etc/skel
Mostly environment files
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
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37. Creating User Accounts (continued)
Table 11-6: Common options to the useradd command
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38. Modifying User Accounts
usermod command: Modify user account information
chage command: Modify password expiration information
Locking an account: Make an account temporarily unusable
Alter password information
chsh command: Change a valid shell to an invalid shell
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39. Modifying User Accounts (continued)
Table 11-7: Common options to the usermod command
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40. Deleting User Accounts
userdel command: Remove user accounts
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
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41. Linux+ Guide to Linux Certification, 2e
Managing Groups
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
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42. Managing Groups (continued)
groups command: List groups that a 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
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43. Managing Groups (continued)
Figure 11-11: Configure users and groups with a desktop environment
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