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NAME

       sync, syncfs - commit buffer cache to disk

SYNOPSIS

       #include <unistd.h>

       void sync(void);

       void syncfs(int fd);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       sync():
           _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

       syncfs():
           _GNU_SOURCE

DESCRIPTION

       sync()  causes  all  buffered modifications to file metadata and data to be written to the
       underlying file systems.

       syncfs() is like sync(), but synchronizes just the file system containing file referred to
       by the open file descriptor fd.

RETURN VALUE

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

ERRORS

       sync() is always successful.

       syncfs() can fail for at least the following reason:

       EBADF  fd is not a valid file descriptor.

VERSIONS

       syncfs() first appeared in Linux 2.6.39.

CONFORMING TO

       sync(): SVr4, 4.3BSD, POSIX.1-2001.

       syncfs() is Linux-specific.

NOTES

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

BUGS

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

SEE ALSO

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

COLOPHON

       This  page  is  part of release 3.35 of the Linux man-pages project.  A description of the
       project, and information about reporting bugs, can be found at  http://man7.org/linux/man-
       pages/.