hdfed - edit the contents of an HDF File
hdfed [-nobackup] [-batch] hdf_file
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
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
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
* 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
* 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,
* 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-
Make no backup file. If this option is omitted, a backup file is
-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.
hdfed -batch $file -nobackup << EOF
info -all group $*
-help Output usage information, as well as a quick list of the hdfedj
hdf(5), ed(1), The HDF Users Guide: /usr/share/doc/libhdf4g/html-
October 31, 1999