nPrefix
strings copied to start of each block.
nUsed
to create uniqueness between hosts and/or devices/files.
nPrefix
Format Control Strings:
u%d = The device name.
%D = The real device name.
u%h = The host name.
%H = The full host name.
u%p = The process ID.
%P = The parent PID.
u%u = The user name.
n Example: prefix="%u@%h (pid %p)"