man > Fcntl(3pm)

NAME
    Fcntl - load the C Fcntl.h defines

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

DESCRIPTION
    This module is just a translation of the C fcntl.h file. Unlike the old mechanism of requiring a
    translated fcntl.ph file, this uses the h2xs 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.

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

EXPORTED SYMBOLS
    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 Exporter.

    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).

    For ease of use also the SEEK_* constants (for seek() and sysseek(), e.g. SEEK_END) and the S_I*
    constants (for chmod() and stat()) are available for import. They can be imported either
    separately or using the tags ":seek" and ":mode".

    Please refer to your native fcntl(2), open(2), fseek(3), lseek(2) (equal to Perl's seek() and
    sysseek(), respectively), and chmod(2) documentation to see what constants are implemented in
    your system.

    See perlopentut to learn about the uses of the O_* constants with sysopen().

    See "seek" in perlfunc and "sysseek" in perlfunc about the SEEK_* constants.

    See "stat" in perlfunc about the S_I* constants.