Server Admin Chapter 10

CUPS

Common UNIX Printing System

IPP

Internet Printing Protocol. Used by CUPS for network printing.

lp command

Sends a print job to a printer

lp -d command

Specifies the destination printer name. If omitted, the default printer is assumed.

CPUS Daemon (cupsd)

Assigns the print job a unique print job ID (spooling)

lpstat -t command

Line printer statistics. Lists all printers and their status.

cupsaccept command

Instructs the printing system to accept print jobs to specified destinations

cupsreject command

Instructs the printing system to reject print jobs to specified destinations

cupsenable command

Starts the named printers

cupsdisable command

Stops the named printers

cupsenable/disable -r command

Indicates a reason for enabling or disabling a named printer

cancel command

Removes print jobs from print queue

cancel -u command

Removes all the jobs sent by a specified user

lpadmin command

Controls or restricts which users can access specific printers

Line Printer Daemon (LPD)

Traditional printing system (this was replaced by CUPS)

lpr command

Line printer remote. Sends documents to a print queue

lpc command

Line printer control. Displays the status of printers

lpq command

Displays print jobs in the print queue

lprm command

Removes print jobs

CUPS vs LPD

CUPS is used in modern versions of Linux. It is more robust and feature rich. It supports LPD and contains versions of the lpd commands.

Which file contains information about each printer installed on the system?

/etc/cups/printers.conf

Which file contains the settings for cupsd?

/etc/cups.cupsd.conf

What is the address for the CUPS web admin tool?

http://servername:631

Printer Classes

CUPS allows you to configure collections of printers that can be used as a single unit (class). A print job is sent to the first available printer.

What are the most common logging daemons on Linux systems?

System log daemon (rsyslogd) and Systemd Journal Daemon (journald)

Syslogd logging format

facility.priority

Facility

Area of the system to listen to

Priority

Refers to the importance of the info

Systemd Journal Daemon (journald)

Replaces the system log daemon on Linux

journalctl command

Used to view events within journald. journald creates a socket at /run/systemd/journal/dev-log

logrotate command

Back up and clear log files from entries stored in /etc/logrotate.conf

/etc/password

Contains user account information

/etc/shadow

Contains encrypted password and expiration info

Format of /etc/password

name:password:UID:GID:GECOS:homedirectory:shell

Which intervals can passwords be set to for expiration?

Min, max, and warn

Min

Indicates the num of days a user must wait before changing their password

Max

Indicates the num of days a user can use the same password without changing it

Warn

Indicates the num of days a user has to change their password before it expires

useradd command

Creates a user account

Most new user info comes from which two files?

/etc/login.defs and /etc/default/useradd

Skeleton Directory

/etc/skel. Contains files that are copied to all new users' home directories when created

usermod command

Modify user account information

chage command

Modify password expiration information

Usermod -L username command

Locks an account

passwd -l username command

Locks an account

chsh command

Changes default shell to a non-interactive program (also locking a user account)

userdel command

Deletes a user account

userdel -r command

Removes the home directory for the user and its contents

What happens to files that were previously owned by a user who has been deleted?

The UID stays the same, but any future user that is given the same UID will own the files.

groupadd command

Adds groups

groupadd -G command

Adds members to a group

Which file is used to edit groups for a user?

/etc/group

groupmod command

Modifies the group name and GID

groupdel command

Removes a group from the system

usermod -aG group1 maryj

Adds maryj to group 1 (-aG preserves the members' existing group memberships)

id command

Displays a list of GIDs for each group

newgrp command

Temporarily changes the primary group to another group