The gdsSetUnits utility modifies the units and resolution of a GDSII file and exports a new GDSII file
with the new, user defined, units and resolution.
The output file can be the same as the input file or a new file name.
gdsSetUnits Command Line Syntax
To see the gdsSetUnits command line syntax you can execute gdsSetUnits with the -h option:
$ gdsSetUnits -h
gdsSetUnits v1.00 (rcs 1.101)
(C) 2003 Artwork Conversion Software, Inc. (831) 426-6163
gdsSetUnits [-grid:] -unit: 
X is the new user grid (defaults: inch:1000000, um:1000)
name specifies the new unit type; must be one of
um, mm, cm, m, uinch, mils, inch
inputfile and outputfile may be stdin and stdout respectively
where stdin and stdout are denoted by '-'
outputfile may be the same as inputfile
if outputfile is omitted then inputfile will be overwritten