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.IX Title "Fcntl 3perl"
.TH Fcntl 3perl 2024-01-12 "perl v5.38.2" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH NAME
Fcntl \- load the C Fcntl.h defines
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 2
\&    use Fcntl;
\&    use Fcntl qw(:DEFAULT :flock);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
This module is just a translation of the C \fIfcntl.h\fR file.
Unlike the old mechanism of requiring a translated \fIfcntl.ph\fR
file, this uses the \fBh2xs\fR 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.
.SH NOTE
.IX Header "NOTE"
Only \f(CW\*(C`#define\*(C'\fR symbols get translated; you must still correctly
pack up your own arguments to pass as args for locking functions, etc.
.SH "EXPORTED SYMBOLS"
.IX Header "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.
.PP
You can request that the \fBflock()\fR constants (LOCK_SH, LOCK_EX, LOCK_NB
and LOCK_UN) be provided by using the tag \f(CW\*(C`:flock\*(C'\fR.  See Exporter.
.PP
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 \f(CW\*(C`:Fcompat\*(C'\fR.  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).
.PP
For ease of use also the SEEK_* constants (for \fBseek()\fR and \fBsysseek()\fR,
e.g. SEEK_END) and the S_I* constants (for \fBchmod()\fR and \fBstat()\fR) are
available for import.  They can be imported either separately or using
the tags \f(CW\*(C`:seek\*(C'\fR and \f(CW\*(C`:mode\*(C'\fR.
.PP
Please refer to your native \fBfcntl\fR\|(2), \fBopen\fR\|(2), \fBfseek\fR\|(3), \fBlseek\fR\|(2)
(equal to Perl's \fBseek()\fR and \fBsysseek()\fR, respectively), and \fBchmod\fR\|(2)
documentation to see what constants are implemented in your system.
.PP
See perlopentut to learn about the uses of the O_* constants
with \fBsysopen()\fR.
.PP
See "seek" in perlfunc and "sysseek" in perlfunc about the SEEK_* constants.
.PP
See "stat" in perlfunc about the S_I* constants.