I am using GMT 5, and I want to create a map with grid lines using the script below. However, the result has grid lines with two colors, black and white, while I want only the lines without any colors. How can I get just grid lines without color strip white and black
#!/bin/sh
FS=15
RR=115.800283333/116.84011/-9.02833333333/-8.15666666667
BO=a0.2f0/a0.2f0.NseW
PS_NAME=Lombok_3DEW.jpg
GEBCO=SRTM_lombok.grd
LOS=Lombok_3DEW_Vel.grd
fcI=mis.cpt
gmt makecpt -Cpolar -T-0.5/0.5/0.1 -Z -D > $fcI
LB=lombok_fault.gmt
#LIG=legenda_sesar_blue.txt
#-----------------------------------------------
SCALE_LAT=-8.95
SCALE_LON=115.9
SCALE_LENG=10
#-----------------------------------------------
SCALE=${SCALE_LON}/${SCALE_LAT}/${SCALE_LAT}/${SCALE_LENG}
S_VER=a875:Elevation:/
#echo “-10000 200 10000 200” > gray.cpt
gmt grdcut $GEBCO -R$RR -GGRAY
gmt psbasemap -JM$FS -R$RR -B$BO -K > $PS_NAME
gmt grdgradient GRAY -Nt1 -A45 -GGRAY_i
gmt grdimage GRAY -IGRAY_i -R$RR -JM$FS -Cgray.cpt -K -O >> $PS_NAME
gmt grdimage $LOS -R$RR -JM$FS -C$fcI -Q -K -O >> $PS_NAME
gmt pscoast -JM$FS -R$RR -B$BO -L$SCALE -Df -Swhite -W0.3 -K -O >> $PS_NAME
gmt psscale -C$fcI -Dx0.5c/5c+w2.5c/0.2c+v -Bxaf -By+l"(m)" -K -O >> $PS_NAME
gmt psxy $LB -R$RR -JM$FS -W0.7,red -K -O >> $PS_NAME
#legenda
echo “115.85 -8.27 0 3 0 0 utara” | gmt psvelo -R$RR -JM$FS -W5,black -Gblack -A0.12/0.16/0.12 -Se0.2/0.05 -K -O >> $PS_NAME
echo “115.85 -8.2 U” | gmt pstext -R$RR -JM$FS -F+f12p,Helvetica -O >> $PS_NAME
gmt psconvert $PS_NAME -Tj -A
The results of script (focus on grid line)
The results that I want (focus on grid line)