semget(2) [sunos man page]

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,  respec-
	    tively, 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 sem-
		       flg 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  sema-
		       phore 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.

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

SunOS 5.10							    11 Feb 2003 							 semget(2)

Check Out this Related Man Page

SEMGET(2)						      BSD System Calls Manual							 SEMGET(2)

NAME

     semget -- obtain a semaphore id

SYNOPSIS

     #include <sys/sem.h>

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

DESCRIPTION

     Based on the values of key and semflg, semget() returns the identifier of a newly created or previously existing set of semaphores.  The key
     is analogous to a filename: it provides a handle that names an IPC object.  There are three ways to specify a key:

     o	 IPC_PRIVATE may be specified, in which case a new IPC object will be created.

     o	 An integer constant may be specified.	If no IPC object corresponding to key is specified and the IPC_CREAT bit is set in semflg, a new
	 one will be created.

     o	 The ftok(3) function may be used to generate a key from a pathname.

     The mode of a newly created IPC object is determined by OR'ing the following constants into the semflg argument:

     SEM_R	   Read access for user.

     SEM_A	   Alter access for user.

     (SEM_R>>3)    Read access for group.

     (SEM_A>>3)    Alter access for group.

     (SEM_R>>6)    Read access for other.

     (SEM_A>>6)    Alter access for other.

     If a new set of semaphores is being created, nsems is used to indicate the number of semaphores the set should contain.  Otherwise, nsems may
     be specified as 0.

RETURN VALUES

     The semget() system call returns the id of a semaphore set if successful; otherwise, -1 is returned and errno is set to indicate the error.

ERRORS

     The semget() system call will fail if:

     [EACCES]		Access permission failure.

     [EEXIST]		IPC_CREAT and IPC_EXCL were specified, and a semaphore set corresponding to key already exists.

     [EINVAL]		The number of semaphores requested is either less than 1 or greater than the system imposed maximum per set.

     [EINVAL]		A semaphore identifier exists for the argument key, but the number of semaphores in the set associated with it is less
			than nsems, and nsems is non-zero.

     [ENOENT]		No semaphore set was found corresponding to key, and IPC_CREAT was not specified.

     [ENOSPC]		Insufficiently many semaphores are available.

     [ENOSPC]		The kernel could not allocate a struct semid_ds.

LEGACY SYNOPSIS

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

     The include files <sys/types.h> and <sys/ipc.h> are necessary.

SEE ALSO

     semctl(2), semop(2), ftok(3), compat(5)

BSD
								September 12, 1995							       BSD

Linux and UNIX Man Pages

semget(2) [sunos man page]

Check Out this Related Man Page