Manual Pages for UNIX Operating System command usage for man msgctl

System Calls                                            msgctl(2)



NAME
     msgctl - message control operations

SYNOPSIS
     #include 

     int msgctl(int msqid, int cmd, struct msqid_ds *buf);


DESCRIPTION
     The msgctl() function provides a variety of message  control
     operations  as  specified  by  cmd.  The  following cmds are
     available:

     IPC_STAT    Place the current value of each  member  of  the
                 data  structure  associated  with msqid into the
                 structure pointed to by  buf.  The  contents  of
                 this structure are defined in Intro(2).


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

                   msg_perm.uid
                   msg_perm.gid
                   msg_perm.mode /* access permission bits only */
                   msg_qbytes

                 This command can be executed only by  a  process
                 that  has  either the {PRIV_IPC_OWNER} privilege
                 or an effective user ID equal to  the  value  of
                 msg_perm.cuid or msg_perm.uid in the data struc-
                 ture associated with msqid. Only a process  with
                 the  {PRIV_SYS_IPC_CONFIG}  privilege  can raise
                 the value of msg_qbytes.


     IPC_RMID    Remove the message queue identifier specified by
                 msqid  from  the  system and destroy the message
                 queue and data  structure  associated  with  it.
                 This  cmd can only be executed by a process that
                 has an effective user ID either with appropriate
                 privileges  asserted  in  the  effective  set or
                 equal  to  the   value   of   msg_perm.cuid   or
                 msg_perm.uid  in  the  data structure associated
                 with msqid. The buf argument is ignored.


RETURN VALUES




SunOS 5.11          Last change: 22 Mar 2004                    1






System Calls                                            msgctl(2)



     Upon successful completion, msgctl() returns  0.  Otherwise,
     it returns -1 and sets errno to indicate the error.

ERRORS
     The msgctl() function will fail if:

     EACCES       The cmd argument is IPC_STAT and operation per-
                  mission  is  denied to the calling process (see
                  Intro(2)).


     EFAULT       The buf argument points to an illegal address.


     EINVAL       The msqid argument is not a valid message queue
                  identifier;  or the cmd argument is not a valid
                  command  or  is  IPC_SET  and  msg_perm.uid  or
                  msg_perm.gid is not valid.


     EOVERFLOW    The cmd argument is IPC_STAT and uid or gid  is
                  too large to be stored in the structure pointed
                  to by buf.


     EPERM        The cmd argument is IPC_RMID  or  IPC_SET,  the
                  {PRIV_SYS_IPC_OWNER}  privilege is not asserted
                  in the effective set of  the  calling  process,
                  and  is not equal to the value of msg_perm.cuid
                  or msg_perm.uid in the data  structure  associ-
                  ated with msqid.

                  The cmd argument  is  IPC_SET,  an  attempt  is
                  being   made   to  increase  to  the  value  of
                  msg_qbytes,   and   the   {PRIV_SYS_IPC_CONFIG}
                  privilege  is not asserted in the effective set
                  of the calling process.


ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:













SunOS 5.11          Last change: 22 Mar 2004                    2






System Calls                                            msgctl(2)



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | Standard                    | See standards(5).           |
    |_____________________________|_____________________________|


SEE ALSO
     Intro(2), msgget(2),  msgrcv(2),  msgsnd(2),  attributes(5),
     privileges(5), standards(5)











































SunOS 5.11          Last change: 22 Mar 2004                    3