OSU Computational Physics - Unix: Print Queues

9.B:

Text Documents

Printing Files

§ 9.A: ; Print Queues

Unix permits multiple users to have access to the same printer, even if the users are on different computers. This is done by having the print commands route the file you want printed to an active program ("process"), the print queue. The print queue stores this and other files, and sends them to the appropriate printer one-at-a-time.

If the printer is not working, the print queue holds the files until the printer is "up". Sometimes the print queue "goes down" if the printer malfunctions. In that case, the queue must be brought "up", possibly with an explicit software command before printing will resume.

It is generally a good idea to check the status of the print queue. If the queue is very long, or if it is down, it's probably a good idea not to send anything to it.

The line printer queue command lpq tells you the status of the print queue. The -d option, followed by the print queue name, is optional.

Some of the print queues on the Department cluster are

ps	PostScript laser printer in Weniger 497
ps2	PostScript laser printer in Weniger 412

Depending on the way the computers are configured, you can get a variety of responses from an lpq command. As you become more accustomed to print queues, the responses will become clearer:

DEC machines respond with several lines ending with something like:


daphy: Sun Jul 21 11:49:54 1996:
Sun Jul 21 13:09:32 1996: 
no entries

IBM machines respond with several lines ending with something like:


Queue   Dev   Status    Job Files              User         PP %   Blks  Cp Rnk
------- ----- --------- --- ------------------ ---------- ---- -- ----- --- ---
ps2     @goop READY    
ps2: Fri Jul 26 12:26:45 1996: 
ps2     ps2   READY

In both cases the reponse means the print queue has no jobs in it.

When the user rubin has the file cp05.ps in a print queue, a DEC reponse may look like:


daphy: Fri Jul 26 14:47:49 1996: 
Fri Jul 26 14:46:58 1996: Attempting to print dfA601daphy
Rank   Pri Owner      Job  Files                                 Total Size
active 0   rubin      601  cp05.ps                              375122 bytes

An IBM reponse may look like:


Queue   Dev   Status    Job Files              User         PP %   Blks  Cp Rnk
------- ----- --------- --- ------------------ ---------- ---- -- ----- --- ---
ps2     @goop READY    
ps2: Fri Jul 26 14:46:58 1996: Attempting to print dfA601daphy
ps2     ps2   RUNNING     0 601                 0             0  0     1  1   0

Now it's time for you to try the line printer queue command and check the status of the default printer queue:

> lpq

To specify a print queue other than the default, use the -d option followed by the print queue name. How does the the queue for ps look?

> lpq 
-P ps

As we said before, if the queue is down or has many job in it, it's a bad idea to send more jobs to it. If there is another printer available, check its queue and send your job there if its up. In any case, it's a terrible idea to keep sending your job to the printer again and again, just because it did not print out the first time. The queue is probably down, and when it comes up, it will probably print many copies of your job.

Often a printer is out of paper, and you can do something about that. If jobs are not printing, talk to someone in the administration group about fixing the printer or queue.

9.B:

Text Documents

Printing Files

Comments and questions to CP-unix@physics.orst.edu.