Calls the System V IPC function msgrcv to receive a message from
message queue ID into variable VAR with a maximum message size of
SIZE.  Note that when a message is received, the message type as a
native long integer will be the first thing in VAR, followed by the
actual message.  This packing may be opened with unpack("l! a*")
.
Taints the variable.  Returns true if successful, false
on error.  See also SysV IPC in perlipc and the documentation for
IPC::SysV  and IPC::Msg .
Portability issues: msgrcv in perlport.