The name argument points to a string naming a semaphore object. It is unspecified whether the name appears in the file system and is visible to functions that take pathnames as arguments. The name argument conforms to the construction rules for a pathname. If name begins with the slash character, then processes calling sem_open() with the same value of name will refer to the same semaphore object, as long as that name has not been removed. If name does not begin with the slash character, the effect is implementation-dependent. The interpretation of slash characters other than the leading slash character in name is implementation-dependent.
SYSTEM V IPC 提供 SEM_UNDO选项用于此目的