# 3.3. Running JULES¶

The user interface of JULES consists of several files with the extension .nml containing Fortran namelists. These files and the namelist members are documented in more detail in The JULES namelist files. These namelists are grouped together in a single directory. That directory is referred to as the namelist directory for a JULES run.

Once a JULES executable is compiled and the namelists are set up, JULES can be run in one of two ways:

1. Run the JULES executable in the namelist directory with no arguments:

cd /path/to/namelist/dir
/path/to/jules.exe

2. Run the JULES executable with the namelist directory as an argument:

/path/to/jules.exe  /path/to/namelist/dir


Warning

Any relative paths given to JULES via the namelists (e.g. file in JULES_FRAC) will be interpreted relative to the current working directory.

This means that if the user plans to use the second method to run JULES (e.g. in a batch environment), it is advisable to use fully-qualified path names for all files specified in the namelists.

To allow runs to be portable across different machines, it is common to specify data files relative to the namelist directory (e.g. in the point_loobos_* examples supplied with JULES). In this case, JULES must be run using the first method to allow the relative paths to be resolved correctly.

## 3.3.1. Running the Loobos example from a fresh download of JULES¶

1. Move into the JULES root directory (the directory containing includes, src etc.):

$cd /jules/root/dir  2. Build JULES: $ fcm make -f etc/fcm-make/make.cfg

3. Move into the example directory:

$cd examples/point_loobos/  4. Run the JULES executable: $ ../../build/bin/jules.exe