GNU Astronomy Utilities manual

4.1.4.1 Input/Output options

These options are to do with the input and outputs of the various programs.

-h

--hdu

(=STR) The number or name of the desired Header Data Unit or HDU in the input FITS image or images. A FITS file can store multiple HDUs or extensions, each with either an image or a table or nothing at all (only a header). Note that counting of the extensions starts from 0(zero), not 1(one). When specifying the name, case is not important so IMAGE, image or ImAgE are equivalent.

A # is appended to the string you specify for the HDU³⁵ and the result is put in square brackets and appended to the FITS file name before calling CFITSIO to read the contents of the HDU for all the programs in Gnuastro. CFITSIO has many capabilities to help you find the extension you want, far beyond the simple extension number and name. See CFITSIO manual’s “HDU Location Specification” section for a very complete explanation with several examples.

-o

--output

(=STR) The name of the output file or directory. With this option the automatic output names explained in Automatic output are ignored.

-D

--dontdelete

By default, if the output file already exists, it will be silently replaced with the output of this run of all Gnuastro programs. By calling this option, if the output file already exists, the programs will warn you and abort.

-K

--keepinputdir

In automatic output names, don’t remove the directory information of the input file names. As explained in Automatic output, if no output name is specified, then the output name will be made in the existing directory based on your input. If you call this option, the directory information of the input will be kept and the output will be in the same directory as the input. Note that his is only relevant if you are running the program from another directory!

Read in other formats.
GNU Astronomy Utilities manual, November 2015.