In addition to the option to download data products as a tar file Xamin will display a list of separate download commands. Users can then transfer individual data files from the command line or create a download script.
These download commands are listed under the Wget Commands Tab of the Products Cart as seen in this screen grab:
wget is a very useful command with many, many options and it took some time to determine which options were needed to traverse the complicated HEASARC data products directory structure to find and transfer the products.
The following is one of the wget commands listed in the Products Cart.
wget -q -nH -r -l0 -c -N -np -R 'index*' -erobots=off --retr-symlinks --cut-dirs=7 http://heasarc.gsfc.nasa.gov/FTP/chandra/data/science/ao01/cat5//1828/primary/acisf01828_001N004_fov1.fits.gz
We thought some of our users might be interested in knowing exactly what these options do. We used GNU Wget online manual for most of our research.
-q: quiet mode, no output is displayed
-nH: directories created on the user’s system will not be named using the HEASARC host name
-r -10: directories will be searched recursively up to 10 levels down
-c: files only partially downloaded from a previous execution will continue to to downloaded
-N: a file will not be downloaded if a local file of the same name exists and is newer
-np: the search will not ascend up to the parent directory during recursion
-R ‘index*’: unnecessary files will not be downloaded
-erobots=off: do not observe directives from the robots.text file that might prevent downloads
–retr-symlinks: symbolic links are traversed and the pointed-to files are retrieved
–cut-dirs=N: skip N number of the components in the URL directory structure when the directory structure is created on user’s system