How do I Query printer for Postscript from the command line?

Your question is a little brief. Is this a network printer? Do you mean query for postscript version? If so, snmpwalk and snmpget commands could be useful - the first to print various OID's and the second to get specific values. Refer to the manpages for more info.

Connected to laptop. Linux Mint 17. Connected with USB X Centronics cable.

What is make and model no of your printer and what are you trying to adcomplish?

Epson Stylus Color 1520. I am trying to establish if it still has Adobe Postscript on it. 1520's did not normally come with Postscript. It came from a relative who is a professional commercial artist in Silicon Valley. Has Adobe Postscript sticker on it. I have not used it for a few years and am exploring it right now. This is a wide format printer, which would be very expensive to replace.

It appears if I understand Epson website's documentation and have the correct printer the option was a special driver that allowed PostScript software like Adobe to print to the 1520 i.e Epson Stylus RIP software driver. The driver converted PS to raster graphics.

There is a cups raster filter although depending on what linux distribution/cups version it may not be installed by default anymore.

http://www.epson.com/cgi-bin/Store/s...&prodoid=10201

Are you okay with using the gutenprint driver which is available for the Stylus C1520? My CUPS installation also offers a foomatic driver for this model.

Don't know. Do any of those allow it to print true Pantone colors? I took the printer apart today, and discovered there is a CMOS type battery located in the very bowels of the printer. I am guessing I might come to grief if I remove it. On the other hand it's been in there since day one. I don't want to completely take the printer apart again later to replace the battery. The printer originally ran on a G4. When software is installed, whether CUPS or Adobe Postscript, is it installed on the printer itself of in the computer that's running it, or a mix of both places.

AFAIU, CUPS does support colour correction using ICC profiles (if available), but I know little about the process. This is managed via Ghostscript (rendering engine used by CUPS).

http://www.ghostscript.com/doc/9.15/...Management.pdf

CUPS and the printer drivers (filters) reside on the computer doing the printing. The printer simply expects printer-specific language (commands and data), and it is the driver that takes care of this.

The underlying CUPS work flow is better explained here
https://en.wikipedia.org/wiki/CUPS