env.txt

env
main() -> calling env(1), dupe(2), mod (un)setenv(3)

(1) -> (2) +/- -> (3)

getenv() acts on (1)
parse_setenv(), envlist_set() act on (2)

filter: fork, envlistset(private copy), execle (execl_e_)
as it works on a private copy, why keep a dupe env at all?
handler.c uses getenv(clean)
curses requires access to read env for LINES and COLUMNS
where do we envlist_set() that we don't want getenv() to pick up?
envlist_set called: filter.c ncrypt/pgp.c, :setenv
exec called: conn/tunnel.c, filter.c sendlib.c system.c
	tunnel setup, many filters, pipe to sendmail, many external commands
all for hiding PGP variables