1 2:D expanded when var set 3true 4TRUE 5:U expanded when var undef 6true 7TRUE 8:D skipped if var undef 9 10:U skipped when var set 11is set 12:? only lhs when value true 13true 14TRUE 15:? only rhs when value false 16false 17FALSE 18do not evaluate or expand :? if discarding 19is set 20year=2016 month=04 day=01 21date=20160401 22Version=123.456.789 == 123456789 23Literal=3.4.5 == 3004005 24We have target specific vars 25exit status 0 26