fsync(2)                                                           fsync(2)

NAME
     fsync - synchronize file status

SYNOPSIS
     #include <unistd.h>

     int fsync(int fildes);

DESCRIPTION
     fsync() moves all modified data and attributes of fildes to a storage
     device. When fsync() returns, all in-memory modified copies of buffers
     associated with fildes have been written to the physical medium.
     fsync() is different from sync, which schedules disk I/O for all files
     but returns before the I/O completes.

     fsync() should be used by programs that require modifications to a
     file to be completed before continuing. For example, a program that
     contains a simple transaction facility might use fsync() to ensure
     that all changes to a file or files caused by a given transaction were
     recorded on a storage medium.

     fsync() fails if one or more of the following apply:

     EBADF    fildes is not a valid file descriptor open for writing.

     ENOLINK  fildes is on a remote machine and the link to that machine is
              no longer active.

     EINTR    A signal was caught during execution of the fsync() system
              call.

     EIO      An I/O error occurred while reading from or writing to the
              file system.

RESULT
     Upon successful completion, a value of 0 is returned. Otherwise, a
     value of -1 is returned and errno is set to indicate the error.

NOTES
     The way the data reach the physical medium depends on both implementa-
     tion and hardware. fsync() returns when the device driver tells it
     that the write has taken place.

SEE ALSO
     sync(2).










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