semget man page on MirBSD

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SEMGET(2)		   BSD Programmer's Manual		     SEMGET(2)

NAME
     semget - get semaphore set

SYNOPSIS
     #include <sys/types.h>
     #include <sys/ipc.h>
     #include <sys/sem.h>

     int
     semget(key_t key, int nsems, int semflg);

DESCRIPTION
     The 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 semflg.

     The access modes of the created semaphores is specified in semflg by
     OR'ing 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:

     +	 sem_perm.cuid and sem_perm.uid are set to the effective UID of the
	 calling process.

     +	 sem_perm.gid and sem_perm.cgid are set to the effective GID of the
	 calling process.

     +	 sem_perm.mode is set to the lower 9 bits of semflg.

     +	 sem_nsems is set to the value of nsems.

     +	 sem_ctime is set to the current time.

     +	 sem_otime is set to 0.

RETURN VALUES
     semget() returns a non-negative semaphore identifier if successful. Oth-
     erwise, -1 is returned and errno is set to reflect the error.

ERRORS
     [EACCES]	   The caller has no permission to access a semaphore set al-
		   ready associated with key.

     [EEXIST]	   Both IPC_CREAT and IPC_EXCL are set in semflg, and a sema-
		   phore set is already associated with key.

     [EINVAL]	   nsems is less than or equal to 0 or greater than the system
		   limit for the number in a semaphore set.

		   A semaphore set associated with key exists, but has fewer
		   semaphores than the number specified in nsems.
     [ENOSPC]	   A new set of semaphores could not be created because the
		   system limit for the number of semaphores or the number of
		   semaphore sets has been reached.

     [ENOENT]	   IPC_CREAT was not set in semflg and no semaphore set asso-
		   ciated with key was found.

SEE ALSO
     semctl(2), semop(2), ftok(3)

MirOS BSD #10-current	       August 17, 1995				     1
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