// reference

Usage example

mkdir -p ~/pfs-base ~/pfs-session ~/pfs-mnt
echo hello > ~/pfs-base/hello.txt

export SESSION_LAYER_DIR=~/pfs-session
export BASE_LAYER_DIRS=~/pfs-base
prismafs ~/pfs-mnt

cat ~/pfs-mnt/hello.txt        # reads from base layer
echo world > ~/pfs-mnt/new.txt # written to session layer only
ls ~/pfs-session                # new.txt appears here, hello.txt does not