bsd/man/man2/fsync.2

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  34 .\"     @(#)fsync.2     8.1 (Berkeley) 6/4/93
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  36 .Dd June 4, 1993
  37 .Dt FSYNC 2
  38 .Os BSD 4.2
  39 .Sh NAME
  40 .Nm fsync
  41 .Nd "synchronize a file's in-core state with that on disk"
  42 .Sh SYNOPSIS
  43 .Fd #include <unistd.h>
  44 .Ft int
  45 .Fn fsync "int fd"
  46 .Sh DESCRIPTION
  47 .Fn Fsync
  48 causes all modified data and attributes of
  49 .Fa fd
  50 to be moved to a permanent storage device.
  51 This normally results in all in-core modified copies
  52 of buffers for the associated file to be written to a disk.
  53 .Pp
  54 .Fn Fsync
  55 should be used by programs that require a file to be
  56 in a known state, for example, in building a simple transaction
  57 facility.
  58 .Sh RETURN VALUES
  59 A 0 value is returned on success.  A -1 value indicates
  60 an error.
  61 .Sh ERRORS
  62 The
  63 .Fn fsync
  64 fails if:
  65 .Bl -tag -width Er
  66 .It Bq Er EBADF
  67 .Fa fd
  68 is not a valid descriptor.
  69 .It Bq Er EINVAL
  70 .Fa fd
  71 refers to a socket, not to a file.
  72 .It Bq Er EIO
  73 An I/O error occurred while reading from or writing to the file system.
  74 .El
  75 .Sh SEE ALSO
  76 .Xr sync 2 ,
  77 .Xr sync 8 ,
  78 .Xr update 8
  79 .Sh HISTORY
  80 The
  81 .Fn fsync
  82 function call appeared in
  83 .Bx 4.2 .