pcb2gcode example config file based on https://www.baldengineer.com/kicad-to-x-carve-pcb-workflow.html

millproject

# front           = ./grb/cnc_test-F.Cu.gbr
back            = ./grb/cnc_test-B.Cu.gbr
outline         = ./grb/cnc_test-Edge.Cuts.gbr
drill           = ./grb/cnc_test-PTH.drl
output-dir      = ./cnc

# common
metric          = yes
metricoutput    = yes
zsafe           = 5
zchange         = 10
optimise        = yes
zero-start      = yes
mirror-absolute = no
vectorial       = no
dpi             = 1000
software        = LinuxCNC

# mill
zwork           = -0.05
mill-feed       = 600
mill-speed      = 10000
offset          = 0.1
extra-passes    = 0

# drill
zdrill          = -1.6
drill-feed      = 1000
drill-speed     = 10000
milldrill       = no
drill-side      = back
onedrill        = yes
nog81           = yes

# outline
cutter-diameter = 3
zcut            = -1.56
cut-feed        = 250
cut-speed       = 12000
cut-infeed      = 0.5
outline-width   = 0.2
bridges         = 1.0
zbridges        = -0.05
bridgesnum      = 2
cut-side        = back
fill-outline    = yes