While most AIX administrators know how to set up print queues and manage printing through SMIT or the general print commands, there's more to printing on the UNIX system. This article walks through AIX's spooler back-end programs such as piomkpq, piolsvp, lsvirprt, chvirprt, and rmvirprt.

What is a virtual printer?

A virtual printer is simply a piece of software that acts like a printer driver; however, the virtual printer doesn't have to be connected to an actual printer. Sound confusing? Think of a virtual printer as another form of standard output. If you want to create a Portable Document Format (PDF), you can typically open the text document and save it as a PDF. This uses a form of a virtual printer—basically printing the text document to a format that can be saved to file and somewhat protected from other authors. You can use virtual printers to create images from documents, fax documents, or send documents to a queue to be formatted for a specific type of printer. The latter is the form of virtual printer this article discusses.

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I can't find the files! Where are they?

Before diving into the virtual printer commands, you need to know the location of the files discussed in this article. Most of the commands referenced in this article are not in a user's typical PATH environment variable. There are two easy solutions to this minor problem:

• Always type out the full path to the executable.
• Add the path of the virtual printer commands to the user's PATH.

If the commands are to be used regularly, I suggest adding it to the user's PATH. Typically a user's PATH is sourced initially from /etc/environment in AIX and then the user's ${HOME}/.profile for local environment variable updates on login or when the ~/.profile is re-sourced. Considering the administration of printers is typically managed by the root user, it is wiser to modify root's local .profile file rather than affecting all users. If ~root/.profile doesn't exist, feel free to create the file.

First, a word of caution for those new to editing the PATH variable: When adding new directories to the PATH environment variable, it is typically wiser to place the new directory to search at the end of the value of the current PATH rather than the beginning. This may be a given to more seasoned UNIX users, but to novices this can cause real problems if not followed. If you're not familiar with the way the PATH variable works, here's an explanation. When a command is executed, the shell must read the user's PATH environment variable to find the executable. The PATH is read in order from left to right and is colon delimited. If a user's PATH is set to A:B:C:D, the shell first attempts to find the command in directory A. If it isn't found there, the shell moves on to look in directory B and so on.

Here's the problem: In this example, the user's PATH is initially set to /usr/bin:/etc:/usr/sbin. If there are multiple versions of a command (for example, /usr/bin/foo and /usr/local/bin/foo) and the user enters only the command rather than the fully qualified file name, the first instance found in the PATH variable order attempts to execute (/usr/bin/foo in this example). Now say the user wants to add /usr/local/bin to PATH to be able to easily find and execute /usr/local/bin/bar. However, the user adds the new directory to the beginning of PATH (that is, PATH=/usr/local/bin:${PATH}). Execution of bar works great, but now the user gets unexpected results when executing foo. This is because /usr/local/bin/foo is now being executed rather than the original /usr/bin/foo. The proper way to accomplish the user's goals is PATH=${PATH}:/usr/local/bin.

On the typical AIX system, most of the virtual printer commands are in the /usr/lib/lpd/pio/etc and /usr/sbin directories, as shown in Listing 1. So, you can update the PATH to be PATH=${PATH}:/usr/sbin:/usr/lib/lpd/pio/etc.

# find /usr \( -name piomkpq -o -name piolsvp -o -name lsvirprt -o -name chvirprt -o
 -name rmvirprt \) -ls

187195   36 -r-xr-s---  1 root    printq    34894 Sep 16  2002 /usr/sbin/chvirprt
187491   48 -r-xr-xr-x  1 root    printq    47474 Sep 16  2002 /usr/sbin/lsvirprt
187763   44 -r-xr-s---  1 root    printq    41474 Sep 16  2002 /usr/sbin/rmvirprt
98653   40 -r-xr-xr-x  1 bin     bin       40522 May 26  2006 /usr/lib/lpd/pio/etc/piolsvp
98706   36 -r-sr-x---  1 root    printq    32782 Sep 16  2002 /usr/lib/lpd/pio/etc/piomkpq

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Creating a virtual printer queue

Creating a print queue in AIX via command line is extremely easy. By using the piomkpq command, you can quickly create new print queues and add a printer to an existing queue.

Table 1 provides a few switches that you can use when executing piomkpq. For a complete list of switches, please take a look at man piomkpq.

Typically, users specify local, ascii, or file for attachment types. If your AIX system has other attachment types, you can find the attachment type configuration files (with the .attach extension) in /usr/lib/lpd/pio/etc, as shown in Listing 2.

# ls -l /usr/lib/lpd/pio/etc/*.attach

-r--r--r--  1 root   printq    1150 Sep 13 2002  /usr/lib/lpd/pio/etc/ascii.attach
-r--r--r--  1 root   printq    1144 Sep 13 2002  /usr/lib/lpd/pio/etc/file.attach
-r--r--r--  1 root   printq    1182 Jan 17 2003  /usr/lib/lpd/pio/etc/hpJetDirect.attach
-r--r--r--  1 root   printq    1209 Jan 17 2003  /usr/lib/lpd/pio/etc/ibmNetColor.attach
-r--r--r--  1 root   printq    1203 Jan 17 2003  /usr/lib/lpd/pio/etc/ibmNetPrinter.attach
-r--r--r--  1 root   printq    1188 Sep 13 2002  /usr/lib/lpd/pio/etc/local.attach
-r--r--r--  1 root   printq    1094 Sep 13 2002  /usr/lib/lpd/pio/etc/remote.attach
-r--r--r--  1 root   printq    1201 Sep 13 2002  /usr/lib/lpd/pio/etc/xstation.attach

Listing 3 is an example of what the configuration files look like in AIX.

# grep -vE "^#|^[[:space:]]*$"  /usr/lib/lpd/pio/etc/ascii.attach

        # ASCII attachment
        description     =       piobe.cat,4,20;Printer Attached to ASCII Terminal
        add_queue       =       ps_makprt_prt
        add_printer     =       ps_makprt_prt
        seq_num         =       4
        submit_job      =       ps_qprt_fileName
        change_queue    =       ps_chpq_attachName
        change_filters  =       ps_pqfilters_ghostName
        remove_queue    =       ps_rmpq_ghostName_other

Now that you know the basic commands, create a new print queue:

# piomkpq –A local –p ibm6252 –d lp0 –D asc –q ATC_QUEUE

Added print queue 'ATC_QUEUE'.

Now create a new local print queue named ATC_QUEUE with an ASCII data stream for an existing IBM 6252 printer named lp0:

# piomkpq –A local –p ibm6252 –D asc  -Q ATC_QUEUE –d lp1

Added printer 'lp1' to print queue 'ATC_QUEUE'.

Do you see the difference between the first and second examples of piomkpq? It's subtle but important. The first example creates a new print queue using the -q switch. In the second example, I use -Q and tell piomkpq to use an existing queue named ATC_QUEUE. If you're new to UNIX or Linux®, this is a perfect example of why case matters when executing commands. Simply changing the case from q to Q completely changes the command, as shown in the previous example.

To verify the print queues and the appropriate devices were added, take a look at /etc/qconfig, shown in Listing 4. The printer configuration file should list the queues in the order shown in lpstat at the end of the file because they were the last added via piomkpq and not manually added to /etc/qconfig.

ATC_QUEUE:
        device = lp0,lp1
lp0:
        file = /dev/lp0
        header = never
        trailer = never
        access = both
        backend = /usr/lib/lpd/piobe
lp1:
        file = /dev/lp1
        header = never
        trailer = never
        access = both
        backend = /usr/lib/lpd/piobe

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Listing printers

Now that you've created a print queue or added a printer to a queue that already exists, it would be nice to verify the queue was created and see what other queues may already exist on your AIX system. Listing virtual printers on AIX is even simpler than creating them. By using the piolsvp command, you can view existing print queues or available attachment types.

Table 2 provides a few switches that you can use when executing piolsvp. For a complete list of switches, please take a look at man piolsvp.

While talking about piomkpq, I mentioned that you could manually view the attachment type configuration files because the files are ASCII text. If you aren't interested in all of the settings and just want a quick listing, piolsvp is your command, as shown in Listing 5.

# piolsvp –A

# ATTACHMENT TYPE      DESCRIPTION
  local                Printer Attached to Local Host
  remote               Printer Attached to Remote Host
  xstation             Printer Attached to Xstation
  ascii                Printer Attached to ASCII Terminal
  hpJetDirect          Network Printer (HP JetDirect)
  file                 File (in /dev directory)
  ibmNetPrinter        IBM Network Printer
  ibmNetColor          IBM Network Color Printer
  other                User Defined Backend

The following example demonstrates how to display a specific print queue—in this case, print queue ATC_HPLJ5:

# piolsvp -P ATC_HPLJ5 -d

# PRINTER		DESCRIPTION
  hp@ATC_HPLJ5   	hplj-5si (PCL)

Listing 6 shows how you can quickly view all defined print queues, their locations, and descriptions.

# piolsvp -p

# PRINT QUEUE          PRINTER              DESCRIPTION
  PAC06_ps             hp@PAC06             generic (PostScript)
  PAC06_pcl            hp@PAC06             generic (PCL Emulation)
  ATC08_pcl            hp@ATC08             generic (PCL Emulation)
  AMDC79_ps            hp@AMDC79            hplj-4000 (PostScript)
  LAB125_pcl           hp@LAB125            hplj-4000 (PCL)
  LAB125_ps            hp@LAB125            hplj-4000 (PostScript)
  ATC_HPLJ5pcl         hp@ATC_HPLJ5         hplj-5si (PCL)
  ATC_HPLJ5PS          hp@ATC_HPLJ5         hplj-5si (PostScript)
  ATC_QUEUE            lp0                  IBM 6252 Impactwriter
                       lp1                  IBM 6252 Impactwriter

The following example queries the attachment configuration for queue AMDC79_ps for a field named add_queue. Because the queue is using an attachment type of hpJetDirect, the file /usr/lib/lpd/pio/etc/hpJetDirect.attach is searched.

# piolsvp -P qaljlab1_pcl -nadd_queue

hp@AMDC79_ps          hpJetDirect          ps_makhp_prt

To simplify, the above query is basically formatting the following grep statement:

# grep "add_queue"  /usr/lib/lpd/pio/etc/hpJetDirect.attach

        add_queue       =       ps_makhp_prt

The lpstat command is familiar to most UNIX users. It is a standard command on most UNIX and Linux systems that displays the status of a printer or several printers, as shown in Listing 7.

# lpstat -W

Queue           Dev            Status       Job Files         User    PP   %  Blks  Cp Rnk
--------------- -------------- -----------  ----------------- ------- ---- -- ----- -- ---
PAC06_ps        hp@PAC06       READY
PAC06_pcl       hp@PAC06       READY
ATC08_pcl       hp@ATC08       READY
AMDC79_ps       hp@AMDC79      READY
LAB125_pcl      hp@LAB125      READY
LAB125_ps       hp@LAB125      READY
ATC_HPLJ5pcl    hp@ATC_HPLJ5   READY
ATC_HPLJ5PS     hp@ATC_HPLJ5   READY
ATC_QUEUE       lp0            READY
ATC_QUEUE       lp1            READY

You can view the actual configuration file for the print queues you created in /var/spool/lpd/pio/@local/custom:

# ls -l /var/spool/lpd/pio/@local/custom/ATC_QUEUE:lp[[:digit:]]*

-rw-rw-r-- 1 root  printq 7019 Apr 28 10:29 /var/spool/lpd/pio/@local/custom/ATC_QUEUE:lp0
-rw-rw-r-- 1 root  printq 7019 Apr 28 10:31 /var/spool/lpd/pio/@local/custom/ATC_QUEUE:lp1

The configuration files are readable ASCII text. By readable, I mean it's in plain text although it may not make much sense to the novice UNIX user. For example, Listing 8 is the first 20 of 250 lines of ATC_QUEUE:lp0.

# head -20 /var/spool/lpd/pio/@local/custom/ATC_QUEUE:lp0

:056:__FLG::
:625:CB:S[B]DyEn:
:626:CC:S[C]DyEn:
:627:CD:S[D]DyEn:
:629:CF:S[F]DyEn:
:630:CG:S[G]DyEn:
:622:Ca:DyS[G500]I[1810532]EnR[pioattr1.cat,1,631;(diag1) - do not print job; display 
main pipeline and pre-processing filter,(diag2) - do not print job; display all pipelines 
and filters,(display) - print job; display all pipelines and filters,(ignore) - print job;
ignore stderr produced by filters,(normal) - print job; exit if filters produce stderr=
-a1,-a0\x27 \x27-A3,-a0\x27 \x27-A2,-a0\x27 \x27-A0,-a0\x27 \x27-A1]:%?%G_a%t-a%I_a%e-a%
I_a\x27 \x27-A%I_A%;
:013:_A:DnEnR[0,1,2,3]:1
:789:_E:S[B020]I[1810501]%IWY:!
:621:_H:S[F350]I[1810503]Dy:
:791:_J:S[C950]I[1810533]%IWY:+
:792:_K:S[B030]I[1810550]%IWY:!
:793:_L:S[D020]I[1810504]%IWY:+
:036:_O:Dn:2
:794:_W:S[B025]I[1810506]%IWY:!
:795:_X:S[D030]I[1810507]EtL[/usr/bin/ls -1 /usr/lib/lpd/pio/trans1 | /usr/bin/sed '/^850
$/d']V[%`WX]:ISO8859-1
:614:_Z:S[D035]I[1810534]%IWY:+
:063:_a:DnEnR[0,1]:0
:635:_b:S[D010]I[1810508]E#G[0..%?%G_l%{0}%=%t%e%G_l%G_t%-%{1}%-%d%;]:0
:658:_d:S[C925]I[1810509]EnL[%IW2]F1:a

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Viewing virtual printer attributes

Now that you've created the virtual printer, take a look at its attributes. To view the attributes of a virtual printer use the lsvirprt command.

Table 3 provides a few switches that you can use when executing lsvirprt. For a complete list of switches, please take a look at man lsvirprt.

Listing 9 uses lsvirprt to list all attributes to the virtual printer created earlier in this article.

# lsvirprt -q ATC_QUEUE -d lp0 | more

Name    Description                                          Value
__FLG   VALUES THAT MAY BE OVERRIDDEN WITH FLAGS ON THE
          COMMAND LINE
CB      -------------- Text Print Options -------------
CC
----------- Job Processing Options ------------
CD
----------- Text Formatting Options -----------
CF
--------- Header/Trailer Page Options ---------
CG
------------- Messages/Diagnostics ------------
Ca      DIAGNOSTIC LEVEL                                     %?%G_a%t-a%I_a%e-a
                                                             %I_a\x27 \x27-A%I_
                                                             A%;
_A      stderr returned? 0: no;  1: yes, & pipelines;  2:    1
          yes, & values, pipelines
_E      DOUBLE-HIGH print?                                   !
_H      HOSTNAME for "PRINTED AT:" on HEADER PAGE
_J      RESTORE printer?                                     +
_K      CONDENSED print?                                     !
_L      WRAP long lines?                                     +
_O      Type of Input Paper Handling (1: manual, 2:          2
          pinwheel, 3: sheetfeed)
_W      DOUBLE-WIDE print?                                   !
_X      CODE PAGE of print file                              ISO8859-1
_Z      Send FORM FEED after each file?                      +
_a      0: Normal Print;  1: Return Flag Values &            0
          Pipeline, But Don't Print
_b      BOTTOM MARGIN (lines)                                0
_d      Print file TYPE                                      a
_e      EMPHASIZED print?                                    !
_f      Pre-processing FILTER NAME
_g      PAGE NUMBER where printing should begin              1
_h      TITLE STRING for 'pr' filter
_i      Number of columns to INDENT                          0
_j      INITIALIZE printer?                                  +
_l      LINES per page                                       66

Notice that I pipe the output to more. This is so you can view all of the attributes for the virtual printer. This virtual printer alone has almost 500 lines of attributes.

If you know what field you want to view, you can append the -a switch with the attribute name. This example looks at lines per page or _l (lower case L):

# lsvirprt -q ATC_QUEUE -d lp0 -a _l

Name    Description                                          Value
_l      LINES per page                                       66

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Changing virtual printer attributes

So far you created a virtual printer and viewed the attributes. Now change one of the virtual printer attributes. The chvirprt command allows you to change a known attribute to an acceptable value.

Table 4 provides a few switches that you can use when executing chvirprt. For a complete list of switches, please take a look at man chvirprt.

After reading the previous section about lsvirprt, you now know how to view the value for lines per page. To expand on that, change the value from 66 to 50 by completing the following steps:

1. First, view the attribute's value so you know what to revert to if needed:

   # lsvirprt -q ATC_QUEUE -d lp0 -a _l Name Description Value _l LINES per page 66

   
   

   Note: It is always a good idea to document the original value and new value in case you need to change back to the original value.

2. Change the number of lines per page from 66 to 50:

   # chvirprt -q ATC_QUEUE -d lp0 -a _l=50

   
   

3. Verify the change was successful:

   # lsvirprt -q ATC_QUEUE -d lp0 -a _l Name Description Value _l LINES per page 50

   
   

As you can see, the value has changed for lines per page.

What if after you make that change the manager of the group that uses the printer wants the value changed to 60 and also wants the maximum number of horizontal and vertical tabs that can be defined changed to 62? Fortunately, you can make both changes at the same time by completing these steps:

1. First, view the attributes' values again so you know what to revert to if needed, as shown in Listing 10.

   
   
   Listing 10. Listing multiple virtual printer attributes
   

   # lsvirprt -q ATC_QUEUE -d lp0 -a _l -a mx -a my Name Description Value _l LINES per page 50 mx Maximum Number of Horizontal Tabs That Can Be 64 Defined my Maximum Number of Vertical Tabs That Can Be 64 Defined

   
   

2. Change the attributes to the desired values:

   # chvirprt -q ATC_QUEUE -d lp0 -a _l=60 mx=62 my=62

   
   

3. Verify the change was successful, as shown in Listing 11.

   
   
   Listing 11. Listing multiple virtual printer attributes
   

   # lsvirprt -q ATC_QUEUE -d lp0 -a _l -a mx -a my Name Description Value _l LINES per page 60 mx Maximum Number of Horizontal Tabs That Can Be 62 Defined my Maximum Number of Vertical Tabs That Can Be 62 Defined

   
   

Maybe it's just me, but I get paranoid that maybe I changed both devices in the queue or accidentally changed the wrong device. Double checking is always a good idea. In Listing 11, notice that only device lp0 changed while lp1 keeps its original values in Listing 12.

# lsvirprt -q ATC_QUEUE -d lp1 -a _l -a mx -a my

Name    Description                                          Value
_l      LINES per page                                       66
mx      Maximum Number of Horizontal Tabs That Can Be        64
          Defined
my      Maximum Number of Vertical Tabs That Can Be          64
          Defined

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Removing virtual printers

Whether you entered the incorrect queue name, no longer need the print queue, or simply want to see how to remove a queue, removing a virtual print queue in AIX is easy. IBM provides the rmvirprt command to accommodate the curious administrator.

To remove the two virtual print queues previously created in this article, simply execute these commands:

# rmvirprt -q ATC_QUEUE -d lp1
# rmvirprt -q ATC_QUEUE -d lp0

By executing rmvirprt, you simply remove the virtual printer assigned to the print queue. The print queues will still exist, but when you look at the printers again the descriptions are gone, as shown in Listing 13. This is because the virtual printer configuration files have been removed via rmvirprt.

# piolsvp -p

# PRINT QUEUE          PRINTER              DESCRIPTION
  PAC06_ps             hp@PAC06             generic (PostScript)
  PAC06_pcl            hp@PAC06             generic (PCL Emulation)
  ATC08_pcl            hp@ATC08             generic (PCL Emulation)
  AMDC79_ps            hp@AMDC79            hplj-4000 (PostScript)
  LAB125_pcl           hp@LAB125            hplj-4000 (PCL)
  LAB125_ps            hp@LAB125            hplj-4000 (PostScript)
  ATC_HPLJ5pcl         hp@ATC_HPLJ5         hplj-5si (PCL)
  ATC_HPLJ5PS          hp@ATC_HPLJ5         hplj-5si (PostScript)
  ATC_QUEUE            lp0                  
                       lp1

In addition the printer queue descriptions being removed, notice the actual virtual printers are removed from the /var/spool/lpd/pio/@local/custom spool directory:

# ls -l /var/spool/lpd/pio/@local/custom/ATC_QUEUE:lp[[:digit:]]*

ls: 0653-341 The file /var/spool/lpd/pio/@local/custom/ATC_QUEUE:lp[[:digit:]]* does not 
exist.

To remove a print queue after the virtual printer has been removed, follow these steps:

1. View the printer queue in question:

   # lsque -q ATC_QUEUE ATC_QUEUE: device = lp0,lp1

   
   

2. Remove the printer queue devices:

   # rmquedev -d lp1 -q ATC_QUEUE # rmquedev -d lp0 -q ATC_QUEUE

   
   

3. Verify the printer queue devices have been removed:

   # lsque -q ATC_QUEUE ATC_QUEUE:

   
   

4. After you remove all devices from the print queue, remove the actual queue:

   # rmque -q ATC_QUEUE

   
   

To verify the virtual printer(s), printer devices, and print queues have been removed, do the following:

1. Verify the printer queue has been removed via lsque.

   # lsque -q ATC_QUEUE lsque: (FATAL ERROR): 0781-193 Queue ATC_QUEUE: not found in qconfig file. Not printed.

   
   
2. Verify the printer queue and devices have been removed via piolsvp, as shown in Listing 14.
   
   Listing 14. Displaying all print queues
   

   # piolsvp -p # PRINT QUEUE PRINTER DESCRIPTION PAC06_ps hp@PAC06 generic (PostScript) PAC06_pcl hp@PAC06 generic (PCL Emulation) ATC08_pcl hp@ATC08 generic (PCL Emulation) AMDC79_ps hp@AMDC79 hplj-4000 (PostScript) LAB125_pcl hp@LAB125 hplj-4000 (PCL) LAB125_ps hp@LAB125 hplj-4000 (PostScript) ATC_HPLJ5pcl hp@ATC_HPLJ5 hplj-5si (PCL) ATC_HPLJ5PS hp@ATC_HPLJ5 hplj-5si (PostScript)

   
   
3. Finally, verify the printer queues have been removed via lpstat, as shown in Listing 15.
   
   Listing 15. Viewing print queues with lpstat
   

   # lpstat -W Queue Dev Status Job Files User PP % Blks Cp Rnk -------------- -------------- -------- ------ ------- ---------- ---- -- ----- -- --- PAC06_ps hp@PAC06 READY PAC06_pcl hp@PAC06 READY ATC08_pcl hp@ATC08 READY AMDC79_ps hp@AMDC79 READY LAB125_pcl hp@LAB125 READY LAB125_ps hp@LAB125 READY ATC_HPLJ5pcl hp@ATC_HPLJ5 READY ATC_HPLJ5PS hp@ATC_HPLJ5 READY

   
   

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Conclusion

After reading this article, you should have a better understanding of what virtual printers are in AIX, how to create them, and how to modify or manage their devices and queues. Knowing more about the printers and the queues set up on your system is important. A lot of people don't realize how many settings you can easily change on a queue. You may be able to make someone's day by modifying a printer to suit that person's needs. Good luck!

Resources

Learn

• Check out IBM's Systems Information Center page about virtual printer attributes.
  
  
• See IBM's Commands Reference page for more information about the following:
  • lsvirprt
  • piolsvp
  • piomkpq
  
  
• For more information about /etc/qconfig see IBM's file reference.
  
  
• The AIX and UNIX developerWorks zone provides a wealth of information relating to all aspects of AIX systems administration.
  
  
• Stay current with developerWorks technical events and webcasts.
  
  
• Browse the technology bookstore for books on these and other technical topics.
  
  

Get products and technologies

• Download IBM product evaluation versions or explore the online trials in the IBM SOA Sandbox and get your hands on application development tools and middleware products from DB2®, Lotus®, Rational®, Tivoli®, and WebSphere®.
  
  

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Table of contents

• What is a virtual printer?
• I can't find the files! Where are they?
• Creating a virtual printer queue
• Listing printers
• Viewing virtual printer attributes
• Changing virtual printer attributes
• Removing virtual printers
• Conclusion
• Resources
• About the author
• Comments

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