the.com/unset
The state of a thing that was never told what it should be.
means A variable, value, or option that exists without having been assigned anything yet.
from From the verb set plus the negating prefix un-, both ancient English roots; the technical sense crystallized in programming, where unset is a specific, queryable nothing distinct from zero or empty.
Not the same as nullUnset means never assigned, null means deliberately nothing.
Shell commandIn Bash, unset actively deletes a variable.
Default stateEverything is unset before it is anything.