HDFED(1)						      General Commands Manual							  HDFED(1)

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 pro-
       vide 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, off-
	      sets, 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 asso-
	      ciated   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  informa-
	      tion 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)