h5jam - Add a user block to a HDF5 file
h5jam -u user_block -i in_file.h5 [-o out_file.h5] [--clobber]
h5jam concatenates a user_block file and an HDF5 file to create an HDF5
file with a user block. The user block can be either binary or text.
The output file is padded so that the HDF5 header begins on byte 512,
1024, etc.. (See the HDF5 File Format.)
If out_file.h5 is given, a new file is created with the user_block
followed by the contents of in_file.h5. In this case, infile.h5 is
If out_file.h5 is not specified, the user_block is added to in_file.h5.
If in_file.h5 already has a user block, the contents of user_block will
be added to the end of the existing user block, and the file shifted to
the next boundary. If --clobber is set, any existing user block will be
Create new file, newfile.h5, with the text in file mytext.txt as the
user block for the HDF5 file file.h5.
h5jam -u mytext.txt -i file.h5 -o newfile.h5
Add text in file mytext.txt to front of HDF5 dataset, file.h5.
h5jam -u mytext.txt -i file.h5
Overwrite the user block (if any) in file.h5 with the contents of
h5jam -u mytext.txt -i file.h5 --clobber
h5jam 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),