The systems at HPC2N predominantly run various versions of Linux. If you have no experience with that, there are several good online sources that can be used to familiarize yourself with the basic commands.
The default shell at HPC2N is bash (Bourne Again SHell), and it is recommended to use that, since it is the only one that is fully supported by the batch system. You can find some information about bash here:
Your home directory at HPC2N is placed on an (Andrew File System) AFS. This file system is backed up regularly. AFS is a distributed networked file system, which was developed for security and scalability.
Most differences between AFS and traditional networked systems (like NFS) are transparent. Two important differences between AFS and NFS are:
You can read more about AFS here, and about the files system at HPC2N in general, here.
Permissions in AFS is applied solely to directories, and not to files
Setting the Unix-permissions makes no difference, only the AFS ACL permissions is of importance
The majority of software on HPC2N are loaded with modules. This means the paths and any needed environment variables are set through the module load <program> command. You can read more about modules here.
Running the command 'env' give you a list of the paths and environment variables that are currently set in your shell. You can read more about environment variables at HPC2N here - and about the SNIC environment variables here.