"But I'm just sending data to Windows - why doesn't the
Windows printer driver just take care of it?"
I probably hear that question at least a dozen times a year.
Somebody wants to send Unix/Linux print jobs through Samba to
a shared Windows printer and it's not working. Why not?
Well, if the printer is a so called GDI, Windows-only (
sometimes called host-based) printer, the reason is simple:
you aren't giving the driver what it wants.
GDI printer drivers expect GDI data, a Microsoft format that
is used both for displays and printers. It's basically a bit
map of the page to be printed, but what's more important is
what it is not: it isn't text, it isn't PostScript and it isn't PCL.
The driver that Windows sends the GDI data to can't handle anything
complicated like that; it can't convert text to graphics, can't
draw lines from vector descriptions, etc. It needs GDI data
and that's that.
You'd think that there would be things that convert arbitrary
data (text? PostScript?) to GDI. In fact, if you are even vaguely
familiar with Linux, you would immediately think that
GhostScript has an output that will produce GDI. You'd
be right, too, except that it's apparently only available on
Windows Ghostscript. That's called "mswinpr2", and you'd use
it in combination with Redmon (a Windows print redirector)
to do the translation.
Creating a Virtual Postscript Printer in Windows using Ghostscript for
You could also use PrintFile
but again, that's done on the Windows side.
You'd think that the easy way to do this would be to produce GDI
output on the Linux side and then ship that through Samba to unmodified
Windows machines. Or that's what I'd think anyway, and tantalizingly
enough, "gs --help" lists "gdi" as one of its output formats. However,
it looks to me like that produces PJL files. Unless I'm horribly
misunderstanding what GDI looks like (see GDI printers under Linux), this isn't the answer.
There ARE Linux drivers for some GDI printers. These seem to
be printer specific and don't solve the general problem of shipping to
any old Windows shared printer. There's also a "libgdiplus" that's part
of Mono; the description makes you wonder if it could be used to
construct such a general purpose translator.
If anyone reading this knows more than I do about this, please do comment.
At a casual glance, converting to GDI seems like the most direct
method - and indeed it's what the Windows GhostScript does. I suspect
the reason is that the Windows GS mswinpr2 can call upon Windows DLL's to do
it's work, and that's why I wonder if Mono's libgdiplus would be
the answer for that.. but I haven't been able to find out enough
about that to say.
See Printing to PPA printers.
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© 2009-11-07 Anthony Lawrence