Set flag name for connection conn to value val.
Tristate flag is one of "yes", "no" or "maybe", and always defaults to "maybe", which means not to require feature, but use it if available.
PRNG is Pseudo-Random Number Generator. The one used in libyw implementation is good one, using MD5 hash on big entropy pool. See yw_random_add(3) for more details.
Flags defined at the moment:
ZLIB - tristate option to enable/disable zlib link compression.
CRYPT - tristate option to enable/disable link encryption.
HOME - user's home directory, used for default values for other options. It defaults to getenv("HOME").
AUTHORITY - file to fetch authentication information from. It defaults to getenv("YAUTHORITY"), and if that fails to HOME/.Yauthority.
DISPLAY - string in form host%port, where host can be IPv4 or IPv6 hostname or IP number. It defaults to getenv("YDISPLAY"), and if that fails to value from authority file (which, in most cases will be localhost%port).
RANDFILE - value of file, from which fetach some random junk for PRNG initiazlization. It defaults to getenv("RANDFILE"), and if that fails to /dev/urandom.
RANDSEED - file in which to store PRNG state. It defaults to getenv("YRANDSEED"), and if that fails to HOME/.Yrandseed.