Dir=/home/tanpv/Data/QG.25.196/ERA5/MSL
TMP1=1.nc
for iy in {1981..2020}; do
    Vname=MSL_mn_${iy}.nc
    Des_file=${Dir}/${Vname}
    while [[ ! -s "${Des_file}" ]]; do 
       cp msl_monthly.py tmp.py
       sed -i "s|YYYY|${iy}|g" tmp.py
       python tmp.py
       sleep 2
       if [[ -s "${Vname}" ]] ; then
          #cdo -O selname,mx2t ${Vname} ${TMP1}   # Skip other no need variables 
          #mv ${TMP1} ${Vname}
          mv ${Vname} ${Dir}/
       fi
    done
done