[gradsusr] problem for a single colour bar for many plot

[Ismaila Diallo]

Hi grads user's,


Happy new year and my best wishes. So i need a script who help me to plot one 
colour bar for many plot in one page. therefore the plot bar that i use are cbar 

or cbarn or cbarm.
There you have my script with four plot:

sdfopen rain.nc
q file
set display color white
set lon -10 20
set lat 0 25
set mpdset hires
set clevs 0 2 4 6 8 10 12 14 16
set gxout shaded
set vpage 0 5.5 4.25 8.5
define aa=ave(rt,t=1,t=3)
d aa
run cbarn
draw title JJA

set vpage 5.5 11 4.25 8.5


set display color white
set lon -10 20
set lat 0 25
set mpdset hires
set clevs 0 2 4 6 8 10 12 14 16
set gxout shaded
define bb=ave(rt,t=4,t=6)
d bb
draw title JFM

set display color white
set lon -10 20
set lat 0 25
set mpdset hires
set clevs 0 2 4 6 8 10 12 14 16
set gxout shaded
set vpage 0 5.5 0 4.25
define cc=ave(rt,t=7,t=9)
d cc

run cbarn
draw title AMJ

set vpage 5.5 11 0 4.25
set display color white
set lon -10 20
set lat 0 25
set mpdset hires
set clevs 0 2 4 6 8 10 12 14 16
set gxout shaded
define dd=ave(rt,t=10,t=12)
d dd
run cbarn
draw title OND

printim image.jpg
eog image.jpg



There is my script but here for each plot you have a colour bar. Now i would 
like to get one colour bar for all this four plot. How must i do?????
Hope in you great help 

Sincerely
cheers!!!
ismaila