semget(2)							   System Calls 							 semget(2)

NAME

       semget - get set of semaphores

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() function returns the semaphore identifier associated with key.

       A  semaphore  identifier and associated data structure and set containing nsems semaphores (see Intro(2)) are created for key if one of the
       following is true:

	   o	  key is equal to IPC_PRIVATE.

	   o	  key does not already have a semaphore identifier associated with it, and (semflg&IPC_CREAT) is true.

       On creation, the data structure associated with the new semaphore identifier is initialized as follows:

	   o	  sem_perm.cuid, sem_perm.uid, sem_perm.cgid, and sem_perm.gid are set equal to the effective user  ID	and  effective	group  ID,
		  respectively, of the calling process.

	   o	  The access permission bits of sem_perm.mode are set equal to the access permission bits of semflg.

	   o	  sem_nsems is set equal to the value of nsems.

	   o	  sem_otime is set equal to 0 and sem_ctime is set equal to the current time.

RETURN VALUES

       Upon  successful completion, a non-negative integer representing a semaphore identifier is returned. Otherwise, -1 is returned and errno is
       set to indicate the error.

ERRORS

       The semget() function will fail if:

       EACCES	 A semaphore identifier exists for key, but operation permission (see Intro(2)) as specified by the low-order  9  bits	of  semflg
		 would not be granted.

       EEXIST	 A semaphore identifier exists for key but both (semflg&IPC_CREAT) and (semflg&IPC_EXCL) are both true.

       EINVAL	 The nsems argument is either less than or equal to 0 or greater than the system-imposed limit. See NOTES.

		 A semaphore identifier exists for key, but the number of semaphores in the set associated with it is less than nsems and nsems is
		 not equal to 0.

       ENOENT	 A semaphore identifier does not exist for key and (semflg&IPC_CREAT) is false.

       ENOSPC	 A semaphore identifier is to be created but the system-imposed limit on the maximum number of	allowed  semaphores  or  semaphore
		 identifiers system-wide would be exceeded. See NOTES.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ipcrm(1), ipcs(1), rctladm(1M), Intro(2), semctl(2), semop(2), setrctl(2), ftok(3C), attributes(5), standards(5)

NOTES

       The  system-imposed  limit  on  the  value  of  the nsems argument is the maintained on a per-process basis using the process.max-sem-nsems
       resource control.

       The system-imposed limit on the number of semaphore identifiers is maintained on a per-project basis using the project.max-sem-ids resource
       control. The  zone.max-sem-ids resource control limis the total number of semaphore identifiers that can be allocated by a zone.

       See rctladm(1M) and setrctl(2) for information about using resource controls.

SunOS 5.11							    14 Aug 2006 							 semget(2)