On 05-Apr-98 David Hobley spoke unto us all:

# % cat file.ps | gs -q -dNODISPLAY -dNOPAUSE -sDEVICE=deskjet -sOutputFile=-
# 

Like someone else said, you need to specify the file on the command line..  I
use a quick little script that basically goes:

#!/bin/sh
gs <options> $1

If you want to cat file.ps | gs   you can use a "-" instead of the file name,
to get gs to eat stdin.
this is my input filter version (for a stylus 500)

#!/bin/sh
export TEMP=/usr/tmp
exec /usr/pkg/bin/gs -sDEVICE=stcolor -dMicroweave -sDithering="fscmyk" -r360x36
0 -dNOPAUSE -q -sOutputFile="|lpr -h -Plp" stcolor.ps - -c quit

(the export temp is there because gs likes to dump massive temp files (upwards
of 4-5 megs) when building large ps print jobs.. and I dont need my root
partition (or tmp) filled up with it.

---
Tim Rightnour    -  root@garbled.net
http://www.zynetwc.com/~garbled/garbled.html