Run-time can also be influenced with following environment variables
({PREFIX} is normally CLUFTER):

EDITOR
editor to use for correcting invalid results, unconditional manual passes, etc.
(should accept a filename as an argument and block until being quit by user)

{PREFIX}_EXTPLUGINS
directory containing ext(ernal|ending) plugins to look at along the standard
locations;  each plugin should have its root directory there carrying the
standard formats-filters-commands directories hierarchy

{PREFIX}_HASHALGO
algorithm available from hashlib Python standard library, used to generate
a fraction of default output filename from the input content (if the command
arranges so);  it is not meant as a security-sensitive function

{PREFIX}_NOSALT
being paranoid by default, usage of HASHALGO is accompanied by mixing some
additional input in (such as file's mtime) so as to prevent any undesired
information leak (say, cluster.conf on input of ccs2pcs can contain password
for a fence device and the digest of original and plaintext modulo obfuscated
password are known, bruteforce attack might be able to reveal the original
incl. the password) -- setting this variable to anything but '0' and 'false'
disables such a paranoid mode (mainly useful for reproducible tests)

-- Plugin specific --

formats/simpleconfig:
{PREFIX}_COROINDENT
can override defaults for both section-subsection and section-option
indentation, which is currently a tabulator for each (i.e., to disable
indenting, just set to an empty string)
