NAME¶

ncmpidiff - compares two netCDF files in parallel

SYNOPSIS¶

mpiexec -n np ncmpidiff [-b] [-q] [-h] [-v var1,...] file1 file2

DESCRIPTION¶

ncmpidiff runs in parallel on np number of MPI processes to compare the contents of the two files and reports the difference to the standard output.

If neither argument -v nor -h is given besides the two file names, the entire files are compared.

When comparing two files entirely, the difference between ncmpidiff and the Unix command diff is that ncmpidiff skips the gaps between variables. The gaps may occur when the alignment feature is used to create a new file. This alignment allows to allocate a larger space for the file header and align the starting file offsets of fixed-size variables (see API ncmpi__enddef and PnetCDF hints). Oftentimes, the contents of gaps are non-zero arbitrary bytes. Thus, two netCDF files (of same or different sizes) can be reported identical by ncmpidiff but not by diff.

OPTIONS¶

-b

Verbose mode - print results (same or different) for all components (file, header, or variables) in comparison

-q

Quiet mode - print nothing on the command-line output. This also disables verbose mode. When in quiet mode, users should check exit status. See below in "EXIT STATUS".

-h

Compare file header only

-v var1,...,varn

Compare only the given list of variables

EXIT STATUS¶

An exit status of 0 means no differences were found, and 1 means some differences were found. Note on VMS-based system, the exit status values are reversed.

SEE ALSO¶

ncmpidump(1), diff(1), pnetcdf(3)

DATE¶

19 Dec 2018