= Running a GiBUU simulation =

After the GiBUU code has been [wiki:compiling compiled] successfully, the executable "GiBUU.x" can be found in the subdirectory "objects/", and a symbolic link to it is placed in the "testRun/" directory. The executable can either be run directly from one of these places, or it can be put into a separate directory of your choice together with a suitable [wiki:jobCards jobcard] (which we recommend for the sake of a cleaner environment).

In principle the executable can also be transferred to a different machine, but it may not necessarily run there (depending on CPU architecture and available libraries). In such a case it can be useful to employ [wiki:compiling#Staticvs.DynamicLinking static linking].


== Program invocation ==

To run GiBUU, just go to the directory where the executable is located and type

{{{
./GiBUU.x < my_setup.job
}}}

The file "my_setup.job" should be a valid GiBUU [wiki:jobCards jobcard], containing all the options and parameters for the desired simulation. Several [wiki:jobCards example jobcards] are provided on the wiki and in the directory [http://gibuu.hepforge.org/svn/releases/release2017/testRun/jobCards/ "testRun/jobCards/"]. If the executable is invoked without specifying a jobcard, i.e. like this

{{{
./GiBUU.x
}}}

then it will just print some version information and exit. When reporting any problems with GiBUU, please provide the information given in this header (which will help us to reproduce the problem).

After starting a simulation with a proper jobcard, it will print a lot of information to the screen and produce several output files. It can be useful to print the output to a log file (for later reference and inspection), which is achieved via

{{{
./GiBUU.x < my_setup.job > log.txt
}}}

This will produce a file "log.txt", which contains all the screen output from GiBUU after the simulation is finished (and be be inspected already while the simulation is running).


== Input files ==

In addition to the jobcard, GiBUU requires several other input files to run (containing various tabulations and data). All these input files and collected in the directory "buuinput", which has to be [wiki:download downloaded] in addition to the actual code. The input directory can be placed in a location of your choice, but its path must be specified in the jobcard, so that GiBUU knows where to find the input files. To achieve this, the switch "path_to_input" in the namelist "&input" must be set to the correct path:

{{{
&input
  ! ... here may be other options ...
  path_to_input = "/full/path/to/buuinput"
/
}}}

If GiBUU stops with this error

{{{
 Path to input files= /full/path/to/buuinput
 Directory does not exist: /full/path/to/buuinput

Stop!
}}}

then you should check that the path you specified is correct and that it actually contains the input files.


== Output files ==

After the simulation is finished, the directory from which it was run will contain various output files that were produced during the simulation and contain the actual physics results. The type and number of these output files strongly depends on the simulation parameters given in the jobcard, and not all of the produced files may be of interest for you (e.g. some of them are just written for debugging and monitoring purposes).

The most important kind of output file is probably the [wiki:LesHouches event output], which contains the full list of particles (with four-vectors etc) that have been produced in the reaction you simulated.

The GiBUU documentation includes a [//Documentation2017/code/robo_output.html list of output files] that can be produced during the simulation.