|SEMGET(2)||System Calls Manual||SEMGET(2)|
key, int nsems,
semget() system call returns the semaphore identifier associated with key.
A new set containing nsems semaphores is
created if either key is equal to
IPC_PRIVATE, or key does not
have a semaphore set associated with it and the
IPC_CREAT bit is set in
The access modes of the created semaphores is specified in semflg as a bitwise OR of zero or more of the following values:
SEM_A alter permission for owner SEM_R read permission for owner SEM_A >> 3 alter permission for group SEM_R >> 3 read permission for group SEM_A >> 6 alter permission for other SEM_R >> 6 read permission for other
If a new set of semaphores is created, the data structure associated with it (the semid_ds structure, see semctl(2)) is initialized as follows:
semget() returns a non-negative semaphore identifier if successful. Otherwise, -1 is returned and errno is set to reflect the error.
IPC_EXCLare set in semflg, and a semaphore set is already associated with key.
A semaphore set associated with key exists, but has fewer semaphores than the number specified in nsems.
IPC_CREATwas not set in semflg and no semaphore set associated with key was found.
|November 15, 2014||OpenBSD-current|