<-d u> is not a valid option
usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]] 
  file1                    File name of the first HDF5 file
  file2                    File name of the second HDF5 file
  [obj1]                   Name of an HDF5 object, in absolute path
  [obj2]                   Name of an HDF5 object, in absolute path
  OPTIONS
   -h, --help              Print a usage message and exit
   -V, --version           Print version number and exit
   -r, --report            Report mode. Print differences
   -v, --verbose           Verbose mode. Print differences, list of objects
   -q, --quiet             Quiet mode. Do not do output
   -c, --compare           List objects that are not comparable
   -N, --nan               Avoid NaNs detection
   -n C, --count=C         Print differences up to C number
   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
                           If the system epsilon is not defined, use the value below:
                               FLT_EPSILON = 1.19209E-07 for float
                               DBL_EPSILON = 2.22045E-16 for double
                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
                           By default, strict equality is used. Use -p or -d to set specific tolerance.

 Modes of output:

  Default mode: print the number of differences found and where they occured
  -r Report mode: print the above plus the differences
  -v Verbose mode: print the above plus a list of objects and warnings
  -q Quiet mode: do not print output

 Compare criteria

 If no objects [obj1[obj2]] are specified, h5diff only compares objects
   with the same absolute path in both files

 The compare criteria is:
   1) datasets: numerical array differences 2) groups: name string difference
   3) datatypes: the return value of H5Tequal 4) links: name string difference
   of the linked value

 Return exit code:

  1 if differences found, 0 if no differences, 2 if error

 Examples of use:

 1) h5diff file1 file2 /g1/dset1 /g1/dset2

    Compares object '/g1/dset1' in file1 with '/g1/dset2' in file2

 2) h5diff file1 file2 /g1/dset1

    Compares object '/g1/dset1' in both files

 3) h5diff file1 file2

    Compares all objects in both files

 Note)  file1 and file2 can be the same file. Use

    h5diff file1 file1 /g1/dset1 /g1/dset2

    to compare '/g1/dset1' and '/g1/dset2' in the same file

