Core management

The classical core management of Flux is quite forward, you have to set the next two variables to use the distribution:

FLUX_NCORES, the number of cores the master uses. FLUX_NCORES is in fact not mandatory, but if it is not declared then Flux will use all the cores of the host node. So, it is usually set to 1 as:
```
export FLUX_NCORES=1
```

FLUX_NODEFILE, the node file path. This file contains the host lists and resources and is provided by the batch scheduler according to the resources requested. For example, PBS node file is accessible via the environment variable PBS_NODEFILE, therefore you can simply set:
```
export FLUX_NODEFILE=$PBS_NODEFILE
```

The recommendation of resources for Flux can be found in What can I expect from parallel computing in Flux.