1SYNC(2)                    Linux Programmer's Manual                   SYNC(2)
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NAME

6       sync, syncfs - commit buffer cache to disk
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SYNOPSIS

9       #include <unistd.h>
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11       void sync(void);
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13       int syncfs(int fd);
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15   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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17       sync():
18           _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
19           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
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21       syncfs():
22           _GNU_SOURCE
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DESCRIPTION

25       sync() causes all buffered modifications to file metadata and  data  to
26       be written to the underlying file systems.
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28       syncfs() is like sync(), but synchronizes just the file system contain‐
29       ing file referred to by the open file descriptor fd.
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RETURN VALUE

32       syncfs() returns 0 on success; on error, it returns -1 and  sets  errno
33       to indicate the error.
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ERRORS

36       sync() is always successful.
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38       syncfs() can fail for at least the following reason:
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40       EBADF  fd is not a valid file descriptor.
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VERSIONS

43       syncfs()  first  appeared in Linux 2.6.39; library support was added to
44       glibc in version 2.14.
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CONFORMING TO

47       sync(): SVr4, 4.3BSD, POSIX.1-2001.
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49       syncfs() is Linux-specific.
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NOTES

52       Since glibc 2.2.2 the Linux prototype for sync() is  as  listed  above,
53       following  the  various  standards.   In  libc4, libc5, and glibc up to
54       2.2.1 it was "int sync(void)", and sync() always returned 0.
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BUGS

57       According to the standard specification  (e.g.,  POSIX.1-2001),  sync()
58       schedules the writes, but may return before the actual writing is done.
59       However, since version 1.3.20 Linux does actually  wait.   (This  still
60       does not guarantee data integrity: modern disks have large caches.)
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SEE ALSO

63       bdflush(2), fdatasync(2), fsync(2), sync(8), update(8)
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COLOPHON

66       This  page  is  part of release 3.53 of the Linux man-pages project.  A
67       description of the project, and information about reporting  bugs,  can
68       be found at http://www.kernel.org/doc/man-pages/.
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72Linux                             2012-05-04                           SYNC(2)
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