Fcntl(3)

NNAAMMEE
       Fcntl - load the C Fcntl.h defines

SSYYNNOOPPSSIISS
           use Fcntl;
           use Fcntl qw(:DEFAULT :flock);

DDEESSCCRRIIPPTTIIOONN
       This module is just a translation of the C fnctl.h file.
       Unlike the old mechanism of requiring a translated
       fnctl.ph file, this uses the hh22xxss program (see the Perl
       source distribution) and your native C compiler.  This
       means that it has a far more likely chance of getting the
       numbers right.

NNOOTTEE
       Only #define symbols get translated; you must still
       correctly pack up your own arguments to pass as args for
       locking functions, etc.

EEXXPPOORRTTEEDD SSYYMMBBOOLLSS
       By default your system's F_* and O_* constants (eg,
       F_DUPFD and O_CREAT) and the FD_CLOEXEC constant are
       exported into your namespace.

       You can request that the flock() constants (LOCK_SH,
       LOCK_EX, LOCK_NB and LOCK_UN) be provided by using the tag
       :flock.  See the Exporter manpage.

       You can request that the old constants (FAPPEND, FASYNC,
       FCREAT, FDEFER, FEXCL, FNDELAY, FNONBLOCK, FSYNC, FTRUNC)
       be provided for compatibility reasons by using the tag
       :Fcompat.  For new applications the newer versions of
       these constants are suggested (O_APPEND, O_ASYNC, O_CREAT,
       O_DEFER, O_EXCL, O_NDELAY, O_NONBLOCK, O_SYNC, O_TRUNC).

       Please refer to your native fcntl() and open()
       documentation to see what constants are implemented in
       your system.