Calls the System V IPC function semctl(2). You'll probably have to say
- use IPC::SysV;
first to get the correct constant definitions. If CMD is IPC_STAT or
GETALL, then ARG must be a variable that will hold the returned
semid_ds structure or semaphore value array. Returns like
ioctl:
the undefined value for error, "0 but true" for zero, or the actual
return value otherwise. The ARG must consist of a vector of native
short integers, which may be created with pack("s!",(0)x$nsem).
See also SysV IPC in perlipc and the documentation for
IPC::SysV and IPC::Semaphore .
Portability issues: semctl in perlport.