In this chapter we will explain how to activate and manage the printer services in RedHat Linux.

RedHat includes the software LPR (originally written at BSD) for managing printing services. There are several UNIX versions that use the system command "lpr", originally introduced in UNIX BSD (Berkeley Software Distributions). UNIX SUN OS, NeXT, BSD, FreeBSD and others use this mode. SCO, UnixWare, AIX (IBM), Interactive, Ultrix (Digital), HP-UX (Hewlett-Packard), IRIX (Silicon Graphics) use the "lpstat" method from AT&T UNIX.

Caldera OpenLinux uses LPRng, different from lpr.

The lpr implementation lets you print through the program "lpr", line printer, that reads the file "/etc/printcap". All system printers are included in this file.

RedHat Linux always installs through the setup program (in the installation phase) the system printer label for your specific printer: "lp" that means line printer is the default printer (supported by the Print Plug-In with the use of the ghostscript interpreter)

The printer "lp" use a filter. Programs like Caldera WABI, Corel WordPerfect include their own "drivers" or printer filters. In these cases you must setup a new printer without the filter.

This is an example for the file "/etc/printcap":

[root@redhead /root]# more /etc/printcap
#
# Please don't edit this file directly unless you know what you are doing!
# Be warned that the control-panel printtool requires a very strict format!
# Look at the printcap(5) man page for more info.
#
# This file can be edited with the printtool in the control-panel.
 

##PRINTTOOL3## REMOTE deskjet 300x300 a4 {} DeskJet Default 1
lp:\
        :sd=/var/spool/lpd/lp:\
        :mx#0:\
        :sh:\
        :rm=192.168.1.60:\
        :rp=ps:\
        :if=/var/spool/lpd/lp/filter:
[root@redhead /root]#

Installing printers on RedHat Linux

RedHat Linux during the installation phase asks for the system printer:

The system printer can be modified at any time using the RedHat printtool program:

If you want to support two or more printers, you have to add the new printer with "printtool".

Now, we will show the standard procedure.

To add a new printer, choose "Add". After will appears the following dialog mask.
 
 

If you choose a "Local Printer" the program test your system the local device.	After this you can complete the entries for the new printer
	... and press the "Select" button

You can choose the printer from the list and fix the "Resolution" and the "Paper Size", and press OK button. After this operation the new printer have been added.

To activate the new printer, you can run the following commands:

[root@heaven /root]# cd /etc/rc.d/init.d
[root@heaven init.d]# lpd reload

that are equivalent to running cd /etc/rc.d/init.d, lpd start; lpd stop. Anyway the new printers will be loaded at the next boot.

You can also run the button "Restart lpd" in the "lpd" menu, or reboot the machine.

RedHat Linux doesn't need any particular command  for activating the printer. After the first printer installation, you can print. Of course it's necessary that the printer daemon  (Print Server) is running on the machine and has been previously activated with "ntsysv".

Nothing else is necessary for printing on RedHat Linux.

For printing, just do the command :

[root@redhead /root]# lpr /etc/passwd

that will print the file "/etc/passwd" on the default printer (local or network printer).
 

Sending a controlling printers jobs "lpr", "lpq" and "lprm"

All UNIX systems or Linux distributions have to set up a default printer. This is valid also for other operating systems.

In RedHat Linux the "default" printer is "lp". This was the reason why we don't have a parameter in the last "lpr" command.

Now we will see the printers on the "heaven" machine :

[root@heaven /root]# more /etc/printcap
# /etc/printcap
#
# Please don't edit this file directly unless you know what you are doing!
# Be warned that the control-panel printtool requires a very strict format!
# Look at the printcap(5) man page for more info.
#
# This file can be edited with the printtool in the control-panel.

#lp|ps:\
#        :sd=/var/spool/lpd/lp:\
#        :mx#0:\
#        :rm=world:\
#        :rp=ps:
ps|rcolorps:\
        :sd=/var/spool/lpd/lp:\
        :mx#0:\
        :rm=world:\
        :rp=ps:
rcolorlp:\
        :sd=/var/spool/lpd/lp:\
        :mx#0:\
        :rm=world:\
        :rp=lp:
rlaserps:\
        :sd=/var/spool/lpd/lp:\
        :mx#0:\
        :rm=earth:\
        :rp=ps:
rlaserlp:\
        :sd=/var/spool/lpd/lp:\
        :mx#0:\
        :rm=earth:\
        :rp=lp:
[root@heaven /root]#

The default printer on the "heaven" machine is a network printer "rm=world" (rm - means remote machine), "rp=ps" (rp - means remote printer). So the the "ps" printer for heaven is the "ps" printer for the machine "world".

In the same way the printer without a filter on the heaven machine is the corresponding printer on the machine "world".

The other printers listed in the file are also network printers attached to the machine "earth".

The lpr printer services are very transparent and clear.

To print, for example, on the printer "rlaserps" (the printer with a filter attached to the machine "earth"), we can run the command:

[root@heaven linux]# lpr -Prlaserps /etc/passwd

To check the status of a printer job, we can run the command :

[root@heaven linux]# lpq -Prlaserps
Printer: rlaserps is ps@earth
Printer: ps@earth
 Queue: 1 printable job
 Server: pid 14868 active
 Unspooler: pid 14869 active
 Status: printed all 906 bytes at 22:09:23
 Rank   Owner/ID                   Class Job  Files               Size Time
active  root@heaven+296                A  296 /etc/passwd          906 22:09:23
[root@heaven linux]#

The command "lpq" without parameters displays the default printer queue. If the default printer is a network printer and the remote machine is down, the "lpq" command cannot tell us about the printer jobs:

[root@heaven /root]# lpq
Host 'world' - cannot open connection to `ps@world' - No route to host

Once the remote machine is up, lpq informs us:

[root@heaven /root]# lpq
Printer: ps@world
 Queue: no printable jobs in queue
 Status: server finished at 19:08:19
[root@heaven /root]#

To find out all the printer jobs on all printers, we can run the command "lpq -a" :

[root@heaven /root]# lpq -a
Printer: ps@heaven (dest ps@world) 'rcolorps'
 Queue: no printable jobs in queue

Printer: ps@world
 Queue: no printable jobs in queue
 Status: server finished at 19:08:19

Printer: rcolorlp@heaven (dest lp@world)
 Queue: no printable jobs in queue

Printer: lp@world
 Queue: no printable jobs in queue
 Status: server finished at 18:02:49

Printer: rlaserps@heaven (dest ps@earth)
 Queue: no printable jobs in queue

Printer: ps@earth
 Queue: no printable jobs in queue
 Status: server finished at 22:09:37

Printer: rlaserlp@heaven (dest lp@earth)
 Queue: no printable jobs in queue

Printer: lp@earth
 Queue: no printable jobs in queue
 Status: server finished at 19:33:12
[root@heaven /root]#

The StarOffice printer jobs are listed as stdin (Standard Input) printer jobs :

[root@world /root]# lpq
Printer: ps@world
 Queue: 1 printable job
 Server: pid 866 active
 Unspooler: pid 867 active
 Status: printed all 133137 bytes at 08:36:01
 Rank   Owner/ID                   Class Job  Files               Size Time
active  root@world+865                 A  865 (stdin)           133137 08:35:55
[root@world /root]#
 

To remove queued printers jobs, we can run the command "lprm" :

[root@heaven /root]# lpr /etc/printcap
[root@heaven /root]# lpr /etc/printcap
[root@heaven /root]# lpr /etc/printcap
[root@heaven /root]# lpq
Printer: ps@world
 Queue: 3 printable jobs
 Server: pid 1044 active
 Unspooler: pid 1073 active
 Status: printed all 769 bytes at 09:51:24
 Rank   Owner/ID                   Class Job  Files               Size Time
active  root@heaven+975                A  975 /etc/printcap        769 09:51:23
2       root@heaven+976                A  976 /etc/printcap        769 09:51:24
3       root@heaven+977                A  977 /etc/printcap        769 09:51:25
[root@heaven /root]#

The number to "kill" is the "JOB" number (for example "975"). This is the command to do, to kill printer job number "975" :

[root@heaven /root]# lprm 975
Printer ps@world:
checking 'root@heaven+975'
  checking perms 'root@heaven+975'
  dequeued 'root@heaven+975'
killing subserver '1073'
checking 'root@heaven+976'
  checking perms 'root@heaven+976'
  not selecting 'root@heaven+976'
checking 'root@heaven+977'
  checking perms 'root@heaven+977'
  not selecting 'root@heaven+977'
[root@heaven /root]#

If we want to remove all the printer jobs (on all printers), we have to add the parameter "-a" :

[root@heaven /root]# lprm -a
Printer ps@world:
Printer lp@world:
Printer rlaserps@world:
Printer ps@earth:
Printer rlaserlp@world:
Printer lp@earth:
[root@heaven /root]#

The following commands allow us to manage printer jobs on OpenLinux: "lpr", "lpq", "lprm" and the daemon "lpd" that is executed at boot time.

In order to introduce the reader to all the printer systems in all UNIX, we include a comparison table :
 
 

The AT&T column pertains to the first version. Each UNIX hardware vendor; IBM, DIGITAL, HP, Interactive and SCO modify AT&T UNIX to its special requirements.

The "lpr" command, for example, lets you send multiple copies of the same file, including a title on each page and other special features:

[root@heaven /root]# lpr -he
lpr: Illegal option 'e'
usage summary: %s [ -Pprinter[@host] ] [-(K|#)copies] [-Cclass][-Jinfo]
   [-Raccountname] [-m mailaddr] [-Ttitle] [-i indent]
   [-wnum ][ -Zoptions ] [ -Uuser ] [ -Fformat ] [ -bhkr ]
   [-Ddebugopt ] [ filenames ...  ]
 -b,l        - binary or literal format
 -Cclass  - job class
 -F format   - job format filter
   -c,d,f,g,l,m,p,t,v are also format specifications
 -h          - no header or banner page
 -i indent   - indentation
 -Jinfo   - banner and job information
 -k          - non seKure filter operation, create temp file for input
 -K copies, -# copies   - number of copies
 -m mailaddr - mail error status to mailaddr
 -Pprinter[@host] - printer on host (default environment variable PRINTER)
 -r          - remove named files after spooling
 -w width    - width to use
 -Q          - put 'queuename' in control file
 -Raccntname - accounting information
 -T title    - title for 'pr' (-p) formatting
 -U username - override user name (restricted)
 -V          - Verbose information during spooling
 -Z filteroptions - options to pass to filter
   default job format -Ff
 A filename of the form '-' will read from stdin.
 PRINTER environment variable is default printer.
 

For example, to print two copies of the same file, you can do the following command (the banner is the default) :

[root@heaven /root]# lpr -#2 /etc/passwd
 

How to control print jobs with "lpc"

The LPRng package contains the program "lpc" for controlling printer jobs :

[root@redhead /root]# lpc
lpc> ?
Commands may be abbreviated.  Commands are:

abort   enable  disable help    restart status  topq    ?
clean   exit    down    quit    start   stop    up
lpc>

With "lpc" it's possible to manage printer queues between several printers, move printer jobs from one printer to another, activate, stop or remove printer jobs.

The beginning user doesn't have to use the "lpc" program.

Printing files in various formats: gif, jpg, dvi and man

In RedHat Linux, as stated in the preceding chapters, you use the ghostscript ("gs") program produce printouts.

Is possible to display color Postscript or print Postscript files. With the new ghostscript, it's easy to print a Postscript file.

[root@heaven /root]# lpr chap11.ps
[root@heaven /root]#

Postscript files can be both printed and viewed not only with "gs" (ghostscript) but also with "gv" (ghostview).

[root@heaven /root]# gs chap11.ps

"ghostview" lets you print specific pages from a Postscript file; for example, pages 3 to 5. This is very useful in some situations.

"gv" is very similar to ghostview, but much more evolved.

If we try to print "gif" or "jpg" files, we find a small surprise:

[root@heaven /root]# lpr pullcable.jpg
lpr: Fatal error - cannot print 'pullcable.jpg': unprintable file

[root@heaven /root]# lpr eps/ribbon.gif
lpr: Fatal error - cannot print 'eps/ribbon.gif': unprintable file
[root@heaven /root]#

How can we print these files?

There are two methods. The first is to use a program like Communicator or "xv" and print on the desired printer.

The second method is to use "magic-filters" program, which you'll find at SUNsite. Once these filters are installed, you can use the lpr program to print almost any type of file format, including "gif" and "jpg."

Even if magic filter lets you print some of the formats that we will explain below, we will show an alternative solution that doesn't require the use of these filters.

To print a "man" page, just do this:

[root@heaven /root]# man cc | lpr -Prlaserps

On the Internet (as well as Linux standard documentation), you'll frequently find files in the DVI (Device Independent) format. Examples of files in "dvi" are on the CD in the "FTContribs/Files/TeX" directory.

These files were generated by the "tex" programs, which converts TeX files to DVI (for more information about the TeX format, see Chapter 17. Text Processing on Linux.)

OpenLinux includes several programs for converting these files.

To find out the most important, just enter "dvi" (and then press the ESC key twice, or TAB)

[root@heaven /root]# dvi
dvi2fax    dviconcat  dvihp      dvilj2p    dvilj4l    dvired     dvitodvi   dvitype
dvibook    dvicopy    dvilj      dvilj4     dvips      dviselect  dvitomp
[root@heaven /root]# dvi

The most frequently used utility is certanly "dvips", seeing as OpenLinux and Linux both can easily print these files. To generate a postscript file, you just add a parameter to the command, like this:

[root@heaven TeX]# dvips -o story.ps story
This is dvipsk 5.58f Copyright 1986, 1994 Radical Eye Software
' TeX output 1998.11.19:1900' - story.ps
<tex.pro. [1]
[root@heaven TeX]#

The efault is to send the output directly to the default printer! (This is not always convenient.)

[root@heaven TeX]# dvips story
This is dvipsk 5.58f Copyright 1986, 1994 Radical Eye Software
' TeX output 1998.11.19:1900' - |lpr
<tex.pro. [1]

You can also transform the file to PCL (the language built into HP LaserJet printers).

[root@heaven TeX]# dvilj story
[1]
All done, used font_storage of HP LaserJet: 26240 Bytes
Dynamically allocated storage: 27985 Bytes
52 characters downloaded as soft fonts
[root@heaven TeX]# ll *.lj
-rw-r--r--   1 root     root         6231 Nov 19 19:11 story.lj
[root@heaven TeX]#

The default is to create a file in PCL format with the extension ".lj", which can be printed on a any laser printer.

Solutions to some printing problems

lpr or LPRng under Linux requires the presence of the "lpd" print daemon and a correctly configured "/etc/printcap" file. You then must print with "lpr" or some common program like StarOffice, Communicator, etc.

Nevertheless, creating temporary files, sending the print to the device, the presence or absence of "lo" (local loopback) can temporarily block printing.

You have to look at the active services to determine what happened if a print didn't finish satisfactorily.

• The "lpd" daemon should be active. Check it with this command:

• Run "ntsysv". After you exit the program, reboot the machine.
• To activate it during the current session, just issue the command: "/etc/rc.d/init.d/lpd start"

• If you have a local printer, the service has to be active in the kernel. Check for (lp) in the "/proc/devices" file.


If "lp" is present, you can install the local printer, with printool
 

[root@world /proc]# more devices
Character devices:
 1 mem
 2 pty
 3 ttyp
 4 ttyp
 5 cua
 6 lp
 7 vcs
14 sound
30 socksys

Block devices:
 2 fd
 3 ide0
22 ide1
[root@world /proc]#


Otherwise you need to include the relative drivers in the kernel. In Linux 2.4.2, you need to activate the following:
 

This mask belong to the "Parallel port support" in the main Menu	Then, you need enable "Parallel printer support" in "Character devices"

[root@ftosx1 /root]# more /proc/devices
Character devices:
  1 mem
  2 pty
  3 ttyp
  4 ttyS
  5 cua
  6 lp
  7 vcs
 10 misc
 14 sound
 81 video_capture
128 ptm
136 pts
162 raw
180 usb

Block devices:
  2 fd
  3 ide0
 22 ide1
[root@ftosx1 /root]#
 

• "lo" (loop back) should be active.

• There should be enough free space on disk to create temporary files.

You can run a test print by explicitly sending a file to the device with the command: "cat /etc/passwd > /dev/lp0".

RedHat Linux includes also the "lptest" program. Another test can be "lptest > /dev/lp0"

Exercises

1. Print the file /etc/passwd on the local printer. If you have a network, print on the network printer.
2. Print the DVI file (tesina2.dvi) on a laser printer.
3. Convert the file /etc/passwd to Postscript.

1. How we can remove the last printer job?
2. How can we remove all the printer jobs on all the printers?
3. Is it possible in Linux to move the next printer job from the printer "ps" (local) to the printer "rlaser"?
4. What command lets you visualize all the current jobs on all printers?
5. Is the network service "lo0" necessary to do printers?
6. In UNIX and the Mainframe typically the jobs show a banner page. What is it?
7. What is the file to be modified for changing the printer output?
8. How do the job printers work in Linux? Is there a driver for each printer?
9. List at least 3 possible errors that stop the printer jobs.
10. What is the first verification for printers problems?

Check the Interactive Exam Cram BASE: 
 

Internet Resources for this chapter.

• http://www.bsd.org
• Berkely Software Design
• Printing-HOWTO-html
• Printing-Usage-HOWTO-html
• http://www.linuxprinting.org