SHMCTL(2)                DOMAIN/IX SYS5                 SHMCTL(2)



NAME
     shmctl - shared memory control operations

USAGE
     #include <sys/types.h>
     #include <sys/ipc.h>
     #include <sys/shm.h>

     int shmctl(shmid, cmd, buf)
     int shmid, cmd;
     struct shmid_ds *buf;


DESCRIPTION
     Shmctl provides shared memory control operations as defined
     by various commands (the cmd argument denoted above).  The
     following cmds are available:

          IPC_STAT  Place the current value of each member of the
                    data structure associated with shmid into the
                    structure pointed to by buf.  The contents of
                    this structure are defined in intro(2).
                    {READ}

          IPC_SET   Set the value of the following members of the
                    data structure associated with shmid to the
                    corresponding value found in the structure
                    pointed to by buf:

                      shm_perm.uid
                      shm_perm.gid
                      shm_perm.mode /* only low 9 bits */

                    This cmd can only be executed by a process
                    that has an effective user ID equal to either
                    that of super-user or to the value of
                    shm_perm.uid in the data structure associated
                    with shmid.

          IPC_RMID  Remove the shared memory identifier specified
                    by shmid from the system and destroy the
                    shared memory segment and data structure
                    associated with it.  This cmd can only be
                    executed by a process that has an effective
                    user ID equal to either that of super-user or
                    to the value of shm_perm.uid in the data
                    structure associated with shmid.






Printed 12/4/86                                          SHMCTL-1

SHMCTL(2)                DOMAIN/IX SYS5                 SHMCTL(2)



RETURN VALUE
     A successful call returns zero.  A failed call returns -1
     and sets errno as indicated below.

ERRORS
     Shmctl will fail if one or more of the following is true:

     [EINVAL]  Shmid is not a valid shared memory identifier.

     [EINVAL]  Cmd is not a valid command.

     [EACCES]  Cmd is equal to IPC_STAT and {READ} operation per-
               mission is denied to the calling process.

     [EPERM]   Cmd is equal to IPC_RMID or IPC_SET and the effec-
               tive user ID of the calling process is not equal
               to that of super-user or to the value of
               shm_perm.uid in the data structure associated with
               shmid.

     [EFAULT]  Buf points to an illegal address.

RELATED INFORMATION
     shmget(2), shmop(2)





























SHMCTL-2                                          Printed 12/4/86