shmget(2)                                                  shmget(2)


       NAME
             shmget - get shared memory segment identifier

       SYNOPSIS
             #include <sys/types.h>
             #include <sys/ipc.h>
             #include <sys/shm.h>
             int shmget(key_t key, int size, int shmflg);

       DESCRIPTION
             shmget returns the shared memory identifier associated with
             key.  This identifier is accessible by any process in the
             system, subject to normal access restrictions and the
             permissions set with shmflg.

             A shared memory identifier and associated data structure and
             shared memory segment of at least size bytes [see intro(2)]
             are created for key if one of the following are true:

                   key is equal to IPC_PRIVATE.

                   key does not already have a shared memory identifier
                   associated with it, and (shmflg&IPC_CREAT) is true.

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

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

                   The access permission bits of shm_perm.mode are set
                   equal to the access permission bits of shmflg.
                   shm_segsz is set equal to the value of size.

                   shm_lpid, shm_nattch, shm_atime, and shm_dtime are set
                   equal to 0.

                   shm_ctime is set equal to the current time.

          Return Values
             On success, shmget returns a non-negative integer, namely a
             shared memory identifier.  On failure, shmget returns -1 and
             sets errno to identify the error.



                           Copyright 1994 Novell, Inc.               Page 1

      shmget(2)                                                  shmget(2)


         Errors
            In the following conditions, shmget fails and sets errno to:

            EINVAL         size is less than the system-imposed minimum or
                           greater than the system-imposed maximum.

            EACCES         A shared memory identifier exists for key but
                           operation permission [see intro(2)] as
                           specified by the low-order 9 bits of shmflg
                           would not be granted.

            EINVAL         A shared memory identifier exists for key but
                           the size of the segment associated with it is
                           less than size and size is not equal to zero.

            ENOENT         A shared memory identifier does not exist for
                           key and (shmflg&IPC_CREAT) is false.

            ENOSPC         A shared memory identifier and associated
                           shared memory segment are to be created but the
                           system-imposed limit on the maximum number of
                           shared memory segments system-wide would be
                           exceeded.

            ENOMEM         A shared memory identifier and associated
                           shared memory segment are to be created but the
                           amount of available memory is not sufficient to
                           fill the request.

            EEXIST         A shared memory identifier exists for key but
                           both (shmflg&IPC_CREAT) and (shmflg&IPC_EXCL)
                           are true.

      REFERENCES
            intro(2), shmctl(2), shmop(2), stdipc(3C)

      NOTICES
            The user must explicitly remove shared memory segments after
            the last reference to them has been removed.









                          Copyright 1994 Novell, Inc.               Page 2