Command line tools¶

Two useful command line tools that come with HDF5 are h5dump and h5repack.

h5dump can be used with the -H option to look at the header of a file: see the dimensions, variables, groups. It can also be used to print a text version of any variable in an HDF5 file (e.g. this can be redirected to a text file). When printing a variable (dataset in HDF5) one uses the option -d variable, and the resulting output is the same as in the -H mode, with the variable printed at the end. The NetCDF ncdump program offers an even clearer look into the file (e.g. used with the -h option to print out the header).

The h5repack program can be used to copy and modify the parameters of HDF5 files. It can convert the files between different format versions, compress variables, etc. Of particular importance is the option for rechunking a file. Chunking in HDF5 files can be used to improve performance by changing the disk structures to improve different read patterns. It is analogous to fully or partially transposing the variables along certain dimensions.