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)