Calls the System V IPC function msgctl(2). You'll probably have to say
- use IPC::SysV;
first to get the correct constant definitions. If CMD is IPC_STAT
,
then ARG must be a variable that will hold the returned msqid_ds
structure. Returns like ioctl: the undefined value for error,
"0 but true"
for zero, or the actual return value otherwise. See also
SysV IPC in perlipc and the documentation for IPC::SysV
and
IPC::Semaphore
.