= How to check whether two (netcdf) files are identical =

=== cdo diffv ===

Rather than comparing plots, its faster and more precise to compare whether two netcdf files (i.e. a history or restart file between 2 model versions) are numerically identical. The follow command works on asterix and obelix

{{{ 
cdo diffv   path_file_1   path_file_2 > output_file_name.txt
}}}
ADVANTAGE: the output file tells you which fields are different. Be aware, though that this method works best for smaller netCDF files. If your history file is more than a few megabytes, the output text file may be many hundreds of megabytes. In that case, the md5sum command may be a better option.

DISADVANTAGE: only works for netcdf files 

=== md5sum ===

If you expect that the files are identical (bit by bit) you can use
{{{
md5sum path_file
}}}
as a result you will get a code. Run the same command on the second file and only when the code is identical for both files, the files are exactly the same.

ADVANTAGE: works for all files.

DISADVANTAGE: you only know whether the files are identical or not. If not, you have no idea which fields are different.