Perl 5 version 22.2 documentation
- fcntl FILEHANDLE,FUNCTION,SCALAR
Implements the fcntl(2) function. You'll probably have to say
- use Fcntl;
first to get the correct constant definitions. Argument processing and value returned work just like
ioctlbelow. For example:
You don't have to check for
definedon the return from
ioctl, it maps a
0return from the system call into
"0 but true"in Perl. This string is true in boolean context and
0in numeric context. It is also exempt from the normal -w warnings on improper numeric conversions.
fcntlraises an exception if used on a machine that doesn't implement fcntl(2). See the Fcntl module or your fcntl(2) manpage to learn what functions are available on your system.
Here's an example of setting a filehandle named
REMOTEto be non-blocking at the system level. You'll have to negotiate
$|on your own, though.
Portability issues: fcntl in perlport.