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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)