Instructions for Mercalli

On mercalli @INGV Spack is not installed, and the user has to do it locally in his/her own area.

Moreover, since Python 2.7 is in use by default, while a version >3.6 is required by Spack, a preliminary step must be executed to force Spack to use Python >3.6, in order to avoid getting this error message Spack requires Python 3.6 or higher You are running spack with Python 2.7.5.

add the following line to your ~/.bashrc file:

export SPACK_PYTHON=/soft/centos7/anaconda/2023.03/bin/python

in your home directory, run the following commands to download and configure Spack:
```
git clone -c feature.manyFiles=true https://github.com/spack/spack.git
. spack/share/spack/setup-env.sh
```
Tip

To avoid running the same command every time you open a new terminal, you might want to add this line to your ~/.bashrc file:
```
. ~/spack/share/spack/setup-env.sh
```
create and activate the environment with the following commands:
```
spack env create -d spack_env_name
spack env activate [-p] ~/spack_env_name
```
Note that the -d option will create the environment in the current folder (typically the home folder but can be a dedicated one), while omitting it will result in creating the environment in the default folder (~/spack/var/spack/environments/). The -p is just a flag to visualize the environment is active.
add Python and py-pip to the environment and install them
```
spack add python py-pip
spack -d install
```
In this way, the (last) preferred version of Python will be installed. You can do spack find to see which packages have been installed.
Tip

In case you want to install a specific Python version, you can search and choose the preferred version through the commands
```
spack info python
spack add python@version
```
install Python packages needed to run the workflow in the environment
```
pip install -r /path-to-software/cheese-ptha-master/requirements.txt
```
The file requirements.txt is provided with the workflow.
Warning

You could get the error ModuleNotFoundError: No module named 'pip'. If this is the case, you have to load py-pip before installing the Python packages
```
spack load py-pip
```

The environment is ready. For any new session, of course, it must be activated by the command

spack env activate [-p] ~/spack_env_name

The same line should be inserted within the file load_env.source (see the installation instructions).