Geant4 User's Guide for Application Developers - Geant4 - CERN

Getting Started with Geant4- Running a Simple Example2.7. How to Make an Executable Program2.7.1. Building ExampleN01 in a UNIX EnvironmentThe code for the user examples in Geant4 is placed in the directory $G4INSTALL/examples, where$G4INSTALL is the environment variable set to the place where the Geant4 distribution is installed (set by defaultto $HOME/geant4). In the following sections, a quick overview on how the GNUmake mechanism works inGeant4 will be given, and we will show how to build a concrete example, "ExampleN01", which is part of theGeant4 distribution.2.7.1.1. How GNUmake works in Geant4The GNUmake process in Geant4 is mainly controlled by the following GNUmake script files (*.gmk scriptsare placed in $G4INSTALL/config):architecture.gmkinvoking and defining all the architecture specific settings and paths which are stored in $G4INSTALL/config/sys.common.gmkdefining all general GNUmake rules for building objects and librariesgloblib.gmkdefining all general GNUmake rules for building compound librariesbinmake.gmkdefining the general GNUmake rules for building executablesGNUmakefileplaced inside each directory in the Geant4 distribution and defining directives specific to build a library, aset of sub-libraries, or an executable.Kernel libraries are placed by default in $G4INSTALL/lib/$G4SYSTEM, where $G4SYSTEM specifies thesystem architecture and compiler in use. Executable binaries are placed in $G4WORKDIR/bin/$G4SYSTEM,and temporary files (object-files and data products of the compilation process) in $G4WORKDIR/tmp/$G4SYSTEM. $G4WORKDIR (set by default to $G4INSTALL) should be set by the user to specify the place his/her own workdir for Geant4 in the user area.For more information on how to build Geant4 kernel libraries and set up the correct environment for Geant4, referto the "Installation Guide".2.7.1.2. Building the executableThe compilation process to build an executable, such as an example from $G4INSTALL/examples, is startedby invoking the "make" command from the (sub)directory in which you are interested. To build, for instance,exampleN01 in your $G4WORKDIR area, you should copy the module $G4INSTALL/examples to your$G4WORKDIR and do the following actions:> cd $G4WORKDIR/examples/novice/N01> gmakeThis will create, in $G4WORKDIR/bin/$G4SYSTEM, the "exampleN01" executable, which you can invoke andrun. You should actually add $G4WORKDIR/bin/$G4SYSTEM to $PATH in your environment.2.7.2. Building ExampleN01 in a Windows EnvironmentThe procedure to build a Geant4 executable on a system based on a Windows system is similar to what should bedone on a UNIX based system, assuming that your system is equipped with GNUmake, MS-Visual C++ compilerand the required software to run Geant4 (see "Installation Guide").18