Transcript Part I: Introduction

Printing
 Some printer jargon
 Spooler
• A piece of software
 Dpi
• Dots per inch
 PDL
• Page description languages
 Bitmap
• Common bitmap formats include JPEG, PNG,
TIFF and GIF
Introduction
1-1
Printing
 Some printer jargon (cont)
 RIP
• Raster Image Processor
• Converts PDL documents to a bitmap

Filters
• Programs that modify jobs en route from the spooler
to the printer

Postscript
• The most common PDL found on Unix

PCL
• Exclusively on Hp printers and quite common in PC
world
Introduction
1-2
Types of printers
 By connection interface
 Serial port
 parallel port
 Universal Serial Bus (USB)
 Network
• Full-fledged network interfaces
• Computer can spool directly to the network printer
– Many network laser printers include a lpd server that runs
inside the printer.
• To simplify administration
– Set up a few host to control the printers
– Other machine simply transmit jobs to these print server
machines
Introduction
1-3
BSD Printing
 Redhat and FreeBSD use BSD printing system.
 Daemon lpd
 Accepts print jobs from users or other (remote) lpds
 Processes the jobs
 Sends jobs to an actual printer
 reads /etc/printcap and is started at boot time
 Program lpr allow users to submit print jobs to lpd.
 Lpr and lpd communicate through the unix socket
/dev/printer
 Which printer to use
• Option -Pprinter
• Env $PRINTER
• Default printer lp, or the first one in /etc/printcap
Introduction
1-4
BSD Printing

Spool
• Lpr create two files under the printer’s spool dir
/var/spool/lpd/printername
control file started with cf
data file started with df
Lpr notifies lpd of the job’s existence
 Lpd then check printcap to determine if the
destination is local or remote

• If remote, lpd opens a connection to the remote
machines’ lpd, transfer the cf and df file,and delete
the local copy
• If local, lpd creates a series of UNIX pipes between
the spool file and hardware to transport the data –
filter processes
Introduction
1-5
BSD printing commands
Command
Location
Function
lpq
/usr/bin
Shows print queue contents and status
lpr
/usr/bin
Queues jobs for printing
lprm
/usr/bin
Cancels a queued or printing job
lpc
/usr/sbin
Controls a printer or queue
lpd
/usr/sbin
Schedules and prints jobs
printtool
/usr/bin
Configures the printing system
Introduction
1-6
BSD Printing
 lpc : make administrative changes
 Enable or disable queuing for a particular printer
• enable/disable printer

Enable or disable printing on a particular printer
• start/stop printer

Remove all jobs from a printer’s queue
• clean printer

Move a job to the top of a printer’s queue
• topq printer jobid
• topq printer username

Start, stop or restart the lpd daemon
• restart printer

Get printer status information
• status printer
Introduction
1-7
BSD Printing
 /etc/printcap file
BSD printing system’s master database
 A printer must be described in the printcap file
before jobs can be submitted it.
 Printcap format

• Name:xx=string:xx#number:xx=string… …
Introduction
1-8

Printcap variables
Name
Type
Meaning
Example
sd
string
Spool directory
sd=/var/spool/lpd/howler-lw
lf
string
Error log file
lf=/var/log/lpr
lp
string
Device name
lp=/dev/lp0
af
string
Accounting file
af=/usr/adm/lpr.acct
rm
string
Remote machine name
rm=beast.xor.com
rp
string
Remote printer name
rp=howler-lw
of
string
Output filter
of=/usr/libexec/lpr/lpf
if
string
Input filter
if=/usr/sbin/stylascii
mx
number
Maximum file size
mx#0
Introduction
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System V printing
 Used by HP-UX, SCO Unic, Solaris etc.
 System V spooling subsystem’s major components:
 Spooling daemon: lpsched responsible for carrying out
print requests by sending data to the appropriate
printer.
 User commands
• Initiate print requests: lp
• Cancel a pending request: cancel
• List queue contents: lpstat

Administrative commands
• Accept, reject, enable, disable, lpadmin, lpmove, lpusers
Introduction
1-10
System V printing

Spooling directories under /var/spool/lp/request named
for each printer
• By default the actual file to print is not copied. The
changing or deleting a file before it is printed affects the
final output.
• Use –c option to lp to copy the file to the spool area
 Device classes
 Group similar devices and declare them to be equivalent
to and substitutable for one another.
 Setting the system default destination
 Use the –d option to the lpadmin command
• #lpadmin –dprinter2
• #lpstat –d

User may set the env LPDEST
Introduction
1-11
System V printing
 Obtaining Destination Status Information

Lpstat command
•
•
•
•
•
•
•
•
Accept job or not: -alist
Display the members: -clist
List print requests: -olist
Display the current status: -plist
Display users’ jobs: -ulist
Display the special files: -vlist
Display summary: -s
Display all status info: -t
Introduction
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System V printing
 Controlling print queues
Use accept and reject commands to permit and
inhibit spooling to a print queue.
 Example:

# reject –r “ There is no paper in the entire building …” laserprinter
#accept laserprinter
 Controlling the status of a particular printing
device


Use enable and disable commands followed by a device
Example:
#disable –r “ changing toner cartridge; back by 11” laserpritner
#enable laserprinter
Introduction
1-13
System V printing
 Starting and stopping the print service
 Started automatically at system boottime
• Such as /etc/rc2.d/S80lp

Check if the scheduler is running
• #lpstat –r
 Stop
and start printing service manually
• #lpshut
• #/etc/rc2.d/S80lp start
 Managing printers and destination classes
 Use lpadmin command to define and modify
characteristics of printer devices and classes
• Stop lpsched first
Introduction
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System V printing
• Adding a printer
#lpadmin –p printer –v special-files interface-option
Where interface_option can be
» -e printer
» -m model
» -i interface-path
Example:
#lpadmin –pPS4 –v /dev/tty02 –ePS3
• Modifying and deleting printers
– Option –x removes a printer
– Option –P changes a printer if it is existed.
• Managing Device class
– Use –c option to place a printer into a class
» #lpadmin –pPS2 -claser
Introduction
1-15
System V printing
 Adding a New printer
 Physically connect the printer
 Change the ownership of the special file to the
user lp and change its mode to 600
 Check startup file (s file and K file)
• Make links if they do not exist
Shutdown printing service with lpshut if
running, and then use lpadmin to add the printer
 Start the printer and its queue

• #accept PS3
• #enable PS3

Test the new printer by spooling a small file.
Introduction
1-16
Network Printing
 Sharing printers among systems within a local area
network


Print server: allow users on other hosts send jobs to one
or more of its printers
Clients: send the jobs to remote hosts.
 Between BSD System
 Outgoing
• Set up printcap entry to specify
– the destination host (rm)
– The target printer (rp)

Incoming
• Allow a remote system to print
– /etc/hosts.lpd or /etc/hosts.equiv
Introduction
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Network printing
 Remote printing under Solaris

Outgoing
• Register the remote system name using lpsystem
• Set up a queue using lpadmin

Incoming
• Handled by the Service Access Facility
– Configure the local listen port monitor using pmadm
Introduction
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Practice
 Let’s configure the printer on Solaris
Connect the printer to the network
 Set the printer IP address/netmask
 Define the printer on your Solaris box

• Use lpadmin sun as
#lpadmin –p printername –s systemname
• Or use /usr/sadm/admin/bin/printmgr
Enable the printer
 Print a test page

Introduction
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Exercise
 Configure the printer on Linux with CUPS

CUPS: common Unix printing system
• Dynamic printer detection
– Broadcasts the printer available
• Grouping printers
• Integrating with Windows
Configure it via localhost:631
 Disable the queue
 Disable the printer
 Cancel a job
 Check the print queue

Introduction
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