NAME

       h5unjam - Extract the user block from a HDF5 file

SYNOPSIS

       h5unjam -i in_file.h5 [-u user_block | --delete] [-o out_file.h5]

DESCRIPTION

       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
       written.

EXAMPLE USAGE

       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

RETURN VALUE

       h5unjam 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), h5jam(1).

                                                                                                      h5unjam(1)