phpman > man > fcntl(3p)

Fcntl(3perl)                      Perl Programmers Reference Guide                      Fcntl(3perl)



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.



perl v5.34.0                                 2025-07-25                                 Fcntl(3perl)