CDO

Hi.

I have attached a nc file

When I do cdo -setattribute,time@units="days since 2020-01-21 00:00:00" pr_2020-01-21.nc TEST.nc

I've got this messages, including a Warning:

cdo    setattribute (Warning): Variable >time< not found!
cdo    setattribute: Processed 5040000 values from 1 variable over 1 timestep [0.13s 85MB].

I do not see changes in the new created file.

When I do ncdump- h, This is the result I've got in both files pr_2020-01-21.nc and TEST.nc

dimensions:
        time = UNLIMITED ; // (1 currently)
        lon = 3600 ;
        lat = 1400 ;
variables:
        int time(time) ;
                time:standard_name = "time" ;
                time:units = "seconds since 1970-01-01" ;
                time:calendar = "proleptic_gregorian" ;
                time:axis = "T" ;
        double lon(lon) ;
                lon:standard_name = "longitude" ;
                lon:long_name = "longitude" ;
                lon:units = "degrees_east" ;
                lon:axis = "X" ;
        double lat(lat) ;
                lat:standard_name = "latitude" ;
                lat:long_name = "latitude" ;
                lat:units = "degrees_north" ;
                lat:axis = "Y" ;
        float pr(time, lat, lon) ;
                pr:long_name = "precipitation flux" ;
                pr:units = "kg m-2 s-1" ;
                pr:cell_methods = "time: mean cell: mean" ;
                pr:component = "atmo" ;
                pr:vgrid = "surface" ;

Why is stating the there id not Variable time??