Fermi Gamma-ray Space Telescope

Cicerone: Software - Fermi Science Tools File Structure

The Fermi science tools are installed via installation scripts, and if you follow the instructions presented in the instructions section of this documentation system, you should be able to process Fermi data without any knowledge of the files, libraries and system variables that comprise the analysis environment. However, a concept of what is included in this environment may help you use it, and should facilitate trouble-shooting. At the very least, an understanding of the file structure will explain what the installation of these tools has added to your computer, and what you should leave as-is.

The tools themselves are a series of binaries (files with the compiled programs) that are all in a /bin directory. This /bin directory must be in your 'path,' the list of directories that the operating system searches to find software you (or other software) invoke.

The tools use a set of libraries, some of which are specific to the Fermi science tools. These libraries are linked dynamically to the executable when the tool is run, and therefore the libraries are separate files in their own directory. These library directories must be in the appropriate path.

A parameter file is associated with each science tool that preserves the last value used for each input parameter; thus the last value you used when running that tool is the default when running the tool again. The installation of the tools provides an initial parameter file with common defaults. Thus, the hidden parameters will most likely remain at standard default values provided with the installation of the tools.

The parameter files are called PFILES, and they will be located in two directories. The first directory holds the 'system' parameter files, the defaults that are provided by the installation. The second directory holds the 'local' parameter files, your personal parameter files that are used when you (but not other users) use a tool. System variables provide the location of these directories.

If properly installed, the Fermi Science Tools can be run from any directory, and thus you should be oblivious to the tools' file structure!

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