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diff --git a/man2/fdatasync.2 b/man2/fdatasync.2 new file mode 100644 index 000000000..696e4cab8 --- /dev/null +++ b/man2/fdatasync.2 @@ -0,0 +1,93 @@ +.\" Hey Emacs! This file is -*- nroff -*- source. +.\" +.\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl) +.\" Copyright (C) 1996 Markus Kuhn. +.\" +.\" [This version merged from two independently written pages - aeb] +.\" +.\" Permission is granted to make and distribute verbatim copies of this +.\" manual provided the copyright notice and this permission notice are +.\" preserved on all copies. +.\" +.\" Permission is granted to copy and distribute modified versions of this +.\" manual under the conditions for verbatim copying, provided that the +.\" entire resulting derived work is distributed under the terms of a +.\" permission notice identical to this one. +.\" +.\" Since the Linux kernel and libraries are constantly changing, this +.\" manual page may be incorrect or out-of-date. The author(s) assume no +.\" responsibility for errors or omissions, or for damages resulting from +.\" the use of the information contained herein. The author(s) may not +.\" have taken the same level of care in the production of this manual, +.\" which is licensed free of charge, as they might when working +.\" professionally. +.\" +.\" Formatted or processed versions of this manual, if unaccompanied by +.\" the source, must acknowledge the copyright and authors of this work. +.\" +.\" 1996-04-12 Andries Brouwer <aeb@cwi.nl> +.\" 1996-04-13 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de> +.\" +.TH FDATASYNC 2 1996-04-13 "Linux 1.3.86" "Linux Programmer's Manual" +.SH NAME +fdatasync \- synchronize a file's in-core data with that on disk +.SH SYNOPSIS +.B #include <unistd.h> +.sp +.BI "int fdatasync(int " fd ); +.SH DESCRIPTION +.B fdatasync +flushes all data buffers of a file to disk (before the system +call returns). It resembles +.B fsync +but is not required to update the metadata such as access time. + +Applications that access databases or log files often write a tiny +data fragment (e.g., one line in a log file) and then call +.B fsync +immediately in order to ensure that the written data is physically +stored on the harddisk. Unfortunately, +.B fsync +will always initiate two write operations: one for the newly written +data and another one in order to update the modification time stored +in the inode. If the modification time is not a part of the transaction +concept +.B fdatasync +can be used to avoid unnecessary inode disk write operations. +.SH "RETURN VALUE" +On success, zero is returned. On error, \-1 is returned, and +.I errno +is set appropriately. +.SH ERRORS +.TP +.B EBADF +.I fd +is not a valid file descriptor open for writing. +.TP +.B EIO +An error occurred during synchronization. +.TP +.BR EROFS ", " EINVAL +.I fd +is bound to a special file which does not support synchronization. +.SH BUGS +Currently (Linux 2.2) +.B fdatasync +is equivalent to +.BR fsync . +.SH AVAILABILITY +On POSIX systems on which +.B fdatasync +is available, +.B _POSIX_SYNCHRONIZED_IO +is defined in <unistd.h> to a value greater than 0. (See also +.BR sysconf (3).) +.\" POSIX 1003.1-2001: It shall be defined to -1 or 0 or 200112L. +.\" -1: unavailable, 0: ask using sysconf(). +.\" glibc defines them to 1. +.SH "CONFORMING TO" +POSIX1b (formerly POSIX.4) +.SH "SEE ALSO" +.BR fsync (2) +.br +B.O. Gallmeister, POSIX.4, O'Reilly, pp. 220-223 and 343. |