CDO

#!/usr/bin/env bash

for i in $(seq 1 6); do ls l${i}.nc; cdo -setzaxis,griddes_${i}.txt l${i}.nc out${i}.nc ;done

[[ -f OUT.nc ]] && rm OUT.nc

cdo merge out1.nc out2.nc out3.nc out4.nc out5.nc out6.nc OUT.nc