NAME

       h5jam - Add a user block to a HDF5 file

SYNOPSIS

       h5jam -u user_block -i in_file.h5 [-o out_file.h5] [--clobber]

DESCRIPTION

       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 unchanged.

       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 overwritten.

EXAMPLE USAGE

       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 mytext.txt.

            h5jam -u mytext.txt -i file.h5 --clobber

RETURN VALUE

       h5jam returns the size of the output file, or -1 if an error occurs.

CAVEATS

       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.

SEE ALSO

       h5dump(1), h5ls(1), h5diff(1), h5import(1), gif2h5(1), h52gif(1), h5perf(1), h5unjam(1).

                                                                                                        h5jam(1)