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.\" ========================================================================
.\"
.IX Title "Sync 3pm"
.TH Sync 3pm "2018-11-01" "perl v5.28.0" "User Contributed Perl Documentation"
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.SH "NAME"
File::Sync \- Perl access to fsync() and sync() function calls
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 5
\&  use File::Sync qw(fsync sync);
\&  sync();
\&  fsync(\e*FILEHANDLE) or die "fsync: $!";
\&  # and if fdatasync() is available on your system:
\&  fdatasync($fh) or die "fdatasync: $!";
\&
\&  use File::Sync qw(fsync);
\&  use FileHandle;
\&  $fh = new FileHandle("> /tmp/foo") 
\&      or die "new FileHandle: $!";
\&  ...
\&  $fh\->fsync() or die "fsync: $!";
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \fBfsync()\fR function takes a Perl file handle as its only argument, and
passes its \fBfileno()\fR to the C function \fBfsync()\fR.  It returns \fIundef\fR on
failure, or \fItrue\fR on success. \fBfdatasync()\fR is identical in return value,
but it calls C \fBfdatasync()\fR instead of \fBfsync()\fR, synchronizing only the
data in the file, not the metadata.
.PP
The \fBfsync_fd()\fR function is used internally by \fBfsync()\fR; it takes a file
descriptor as its only argument.
.PP
The \fBsync()\fR function is identical to the C function \fBsync()\fR.
.PP
This module does \fBnot\fR export any methods by default, but \fBfsync()\fR
is made available as a method of the \fIFileHandle\fR class. Note carefully
that as of 0.11, we no longer clobber anything in \fIIO::Handle\fR. You
can replace any calls to \fBIO::Handle::fsync()\fR with \fBIO::Handle::sync()\fR:
  https://rt.cpan.org/Public/Bug/Display.html?id=50418
.SH "NOTES"
.IX Header "NOTES"
Doing \fBfsync()\fR if the stdio buffers aren't flushed (with \f(CW$|\fR or the
\&\fIautoflush\fR method) is probably pointless.
.PP
Calling \fBsync()\fR too often on a multi-user system is slightly antisocial.
.SH "AUTHOR"
.IX Header "AUTHOR"
Carey Evans <\fIc.evans@clear.net.nz\fR>
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBperl\fR\|(1), \fBfsync\fR\|(2), \fBsync\fR\|(2), \fBperlvar\fR\|(1)