Amber topology to box dimensions

awk '/BOX_DIMENSIONS/ {getline;getline;print $2, $3,$4;} {}' target.prmtop

awk '/BOX_DIMENSIONS/ {getline;getline;print sprintf("#$LABELS step a_x a_y a_z b_x b_y b_z c_x c_y c_z o_x o_y o_z s_x s_y s_z s_u s_v s_w\n0   %f 0 0   0 %f 0   0 0 %f   0 0 0  0 0 0  0 0 0",$2,$3,$4)} {}' target.prmtop