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)