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-rw-r--r--lib/kernel/doc/src/file.xml10
1 files changed, 10 insertions, 0 deletions
diff --git a/lib/kernel/doc/src/file.xml b/lib/kernel/doc/src/file.xml
index 1118a8feee..0a4dd3ba47 100644
--- a/lib/kernel/doc/src/file.xml
+++ b/lib/kernel/doc/src/file.xml
@@ -826,6 +826,16 @@
<item>
<p><c>File</c> must be <c>iodata()</c>. Returns an <c>fd()</c> which lets the <c>file</c> module operate on the data in-memory as if it is a file.</p>
</item>
+ <tag><c>sync</c></tag>
+ <item>
+ <p>On platforms that support it, enables the POSIX <c>O_SYNC</c> synchronous I/O flag or its platform-dependent
+ equivalent (e.g., <c>FILE_FLAG_WRITE_THROUGH</c> on Windows) so that writes to the file block until the data has
+ been physically written to disk. Be aware, though, that the exact semantics of this flag differ from platform to
+ platform; for example, neither Linux nor Windows guarantees that all file metadata are also written before the call
+ returns. For precise semantics, check the details of your platform's documentation. On platforms with no
+ support for POSIX <c>O_SYNC</c> or equivalent, use of the <c>sync</c> flag causes <c>open</c> to return
+ <c>{error, enotsup}</c>.</p>
+ </item>
</taglist>
<p>Returns:</p>
<taglist>