One of the strengths of Singularity is the ease of access to network and parallel filesystems without compromising security. The home directory, /home/$USER is mounted automatically. To access other directories and filesystems, they have to be “bound” to a container with corresponding command line option -B source[:target] ; obviously, the target directory should exist, be created first within the container, either when it was built or in a shell session. If the target is omitted, it is assumed to be the same path as the source. The names of the filesystems are specific to the HPC cluster you are running it on.