h5unjam - Extract the user block from a HDF5 file
h5unjam -i in_file.h5 [-u user_block | --delete] [-o out_file.h5]
h5unjam splits an HDF5 file, writing the user block to a file or stdout
and the HDF5 file to an HDF5 file with a header at byte 0 (i.e., with
no user block).
If out_file.h5 is given, a new file is created with the in_file.h5
without the user block. In this case, infile.h5 is unchanged.
If out_file.h5 is not specified, the user_block is removed and
in_file.h5 is rewritten, starting at byte 0.
If user_block is set, the user block will be written to user_block. If
user_block is not set, the user block (if any) will be written to
stdout. If --delete is selected, the user block will not be not
For an HDF5 file, with_ub.h5, with a user block, extract the user block
to user_block.txt and the HDF5 file to wo_ub.h5.
h5unjam -i with_ub.h5 -u user_block.txt -i wo_ub.h5
h5unjam returns the size of the output file, or -1 if an error occurs.
This tool copies all the data (sequentially) in the file(s) to new
offsets. For a large file, this copy will take a long time.
The most efficient way to create a user block is to create the file
with a user block (see H5Pset_user_block), and write the user block
data into that space from a program.
The user block is completely opaque to the HDF5 library and to the
h5jam and h5unjam tools. The user block is simply read or written as a
string of bytes, which could be text or any kind of binary data. It is
up to the user to know what the contents of the user block means and
how to process it.
When the user block is extracted, all the data is written to the
output, including any padding or unwritten data.
This tool moves the HDF5 file through byte copies, i.e., it does not
read or interpret the HDF5 objects.
h5dump(1), h5ls(1), h5diff(1), h5import(1), gif2h5(1), h52gif(1),