NAME

       hdfed - edit the contents of an HDF File

SYNOPSIS

       hdfed [-nobackup] [-batch] hdf_file

DESCRIPTION

       hdfed allows experienced HDF users to manipulate the elements of an HDF file. These manipulations include

       *      Selecting groups and showing information about them.

       *      Dumping group information to output files.

       *      Writing group data to output files.

       *      Deleting groups from HDF files.

       *      Inserting groups in HDF files.

       *      Replacing elements of HDF files.

       *      Editing the labels and descriptions of any element in an HDF file.

       hdfed  is  designed  primarily for users who need to know about HDF files at the level of individual data
       elements. It is not designed to provide a comprehensive high-level view of the contents of an HDF file  -
       other  tools  and utilities should be used for that purpose. To use hdfed one should be familiar with the
       components of an HDF file covered in the HDF Specifications manual.

       The hdfed utility is loosely modeled on ed(1), the UNIX line editor. When hdfed is  invoked,  it  prompts
       the user for commands, as does ed. Also, basic command syntax and description information is available to
       the  user  through hdfed. The most common hdfed commands are used to control the position in the HDF file
       and the format of the information provided.

       The initial view of the file under hdfed consists of a set of tag/reference number pairs. Although  hdfed
       allows  modification  of tags and reference numbers within strict constraints, it will not allow the user
       to arbitrarily modify binary data in the file.

       The following terms and concepts must be understood in order to use hdfed correctly and will be  used  in
       the following discussion about hdfed.

       *      The  data  object  or  object refers to an HDF data object and the data descriptor of that object.
              (i.e., tags, reference numbers, offsets, or lengths.)

       *      The data or data element refers to the record that the data descriptor points to.  For  a  precise
              definition  of  the  data  that  is associated with a given tag consult the HDF Specifications and
              Developer's Guide v3.2 from the HDF WWW home page at http://hdf.ncsa.uiuc.edu/.

       *      The group refers to a predefined collection of  data  objects  that  correspond  to  a  particular
              application.  For  example, a raster image group refers to the collection of objects that are used
              to store all of the information in a raster image set.

       Once an HDF file has been opened by hdfed, the following operations can be performed on  the  data  file,
       among others:

       *      Select an HDF object to examine more closely.

       *      Move forward or backward within the HDF file.

       *      Get information about an object. (tag, reference number, size, label)

       *      Display a raster image using the ICR protocol.

       *      Display the contents of any object.

       *      Delete an object.

       *      Annotate an object with a label or description.

       *      Write an object to a second HDF file.

       *      Write data elements in binary form to a non-HDF file.

       *      Close the file and exit, or open a new file.

       hdfed commands are documented in the Users Guide section on Command-line Utilities.

OPTIONS

       -nobackup
              Make no backup file. If this option is omitted, a backup file is automatically created.

       -batch Input  to  hdfed  is  a  stream  of hdfed commands, rather than interactively.  The -batch flag is
              useful when a group of commonly-used commands are included in a UNIX shell script.  The  following
              is  an  example  of such a script, using the C-shell, that lists information about the groups in a
              specified HDF file.

                      #!/bin/csh -f
                      set file=$1
                      shift
                      hdfed -batch $file -nobackup << EOF
                      info -all group $*
                      close
                      quit
                      EOF
                      echo ""

       -help  Output usage information, as well as a quick list of the hdfedj commands.

SEE ALSO

       hdf(5), ed(1), The HDF Users Guide: /usr/share/doc/libhdf4g/html-userguide/Utils2.html#33.

                                                October 31, 1999                                        HDFED(1)