[NTLUG:Discuss] printing from Linux

[Kevin Brannen]

Charles Cashion wrote:

> I would like to understand the flow of information from a
> program to a printer.


I don't know that I'm the best person to answer this, but I'll give it a 
stab...

> True for False?
> The output from Linux programs is occasionally, frequently,
> most frequently, almost always PostScript?


True that most programs prefer PS.  It is the "lingua franca" in the 
world of Unix printing.

> True for False?
> If you feed PostScript (PS) to a printer that understands PS or
> that pretends to understand PS (emulation), then you will get
> your printout.


True...Unless you get it in a mode where it thinks it's getting text, 
then it will print the PS source (that's happened to me a few times :-) 
but that indicates an error somewhere else, usually in a printer filter 
or bad command-line args where you lie to it.

> True?
> A NON-PS printer that understands raster scan (RS) can be used
> if the computer translates PS to RS.


By RS, I assume you mean the printer's internal/native language?  If 
yes, then True; and this is what happens on all non-PS printers, whether 
in Unix or Windows (and probably Mac too).  Logically, if the printer is 
going to print the correct "image", then it must be told about it 
correctly.  This is why printer drivers are so important, they know how 
to talk to the printer.  Some will do minor translating (margins, 
pagination, etc.).  But going from PS to RS is a major translation, and 
there are programs for that, in all OS worlds.  In the Unix world, the 
most common is Ghostscript.

> True?
> Almost any new printer (ink jet or laser) does raster scan.


I don't know, but I would suspect that is true.  Many lasers printers 
will do PCL and PS, I would guess you'd categorize the PCL part as a RS.

> Options?
> If your printer does not understand PS, then you have several
> options:
>         1. You translate PS to raster scan and send it to
>                 the printer?
>         2. You send your printing to ghostscript and that
>                 converts it to RS
>         3. You send your printing thru pimp and it does the
>                 conversion


Pretty much, there may be others, but I'm not aware of them.  I 
generally use option 2.

> Print Specific file:
> So if you are going to convert PS to RS, you are really
> translating PS to whatever language the printer speaks?


True.

> WHAT I REALLY NEED: If you understand how printing works, and
> you learned it from something you read, I want to know what
> you read. I want to read it.
>
> WHAT HELPS: Most of the time, I have to read something from
> more than one source before I finally understand it. If more
> than one person would suggest something to read, it would
> help. Please let me know what you read that finally caused
> you to understand Linux printing. 


Sorry, I think I just picked most of this up along the way, ya know a 
little and a little there, which is why there's probably a few gaps in 
my answers above.  That being said, I think that if you were to go read 
and learn about CUPS, I think that would answer many of your questions, 
as it's becoming the de-facto standard for printing in the Linux world.  
The KDE help docs discuss CUPS to some extent, you might want to start 
there.  Your Linux distro probably has other docs on CUPS; check your 
CD/DVD in case you didn't install them; or google for them.

I really understand your plight and pain, having experienced it for some 
years.  Fortunately, the low end of PS printers are actually affordable 
now.  If you think about it, you can spend $200 (or less it seems from 
reading the other emails here) and that printer might last you 10 years 
(or at least it would the way I use them which is very little).  
Considering I print so little that I might never have to buy another 
print cartidge, that's $20/year for a guaranteed printing solution.  
Looking at it that way, it doesn't seem so bad; the bad part is that you 
have to pay for all 10 years worth up front.  Still, I'm sure I will end 
up doing that sometime in the next year; I almost never need color so 
that would work for me.  You might want to think about that and see if 
it works for you too.

HTH,
Kevin