Implements the fcntl(2) function. You'll probably have to say
first to get the correct constant definitions. Argument processing and value return works just like
ioctl() below. For example:
use Fcntl; fcntl($filehandle, F_GETFL, $packed_return_buffer) or die "can't fcntl F_GETFL: $!";
You don't have to check for
defined() on the return from
ioctl(), it maps a
0 return from the system call into "
0 but true" in Perl. This string is true in boolean context and
0 in numeric context. It is also exempt from the normal -w warnings on improper numeric conversions.
fcntl() will produce a fatal error if used on a machine that doesn't implement fcntl(2).