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34 .\" @(#)fsync.2 8.1 (Berkeley) 6/4/93
42 .Nd "synchronise changes to a file"
48 .Fn fdatasync "int fd"
55 causes all modified data and attributes of the file referenced by
58 to be moved to a permanent storage device.
59 This normally results in all in-core modified copies
60 of buffers for the associated file to be written to a disk.
64 system call causes all modified data of
66 to be moved to a permanent storage device.
69 the system call does not guarantee that file attributes or
70 metadata necessary to access the file are committed to the permanent storage.
75 should be used by programs that require a file to be
76 in a known state, for example, in building a simple transaction
78 If the file metadata has already been committed, using
80 can be more efficient than
87 calls are cancellation points.
101 is not a valid descriptor.
106 refers to a socket, not to a file.
108 An I/O error occurred while reading from or writing to the file system.
117 system call appeared in
121 system call appeared in
126 system call currently does not guarantee that enqueued
128 requests for the file referenced by
130 are completed before the syscall returns.