Section: Linux Programmer's Manual (2)
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sync, syncfs - commit filesystem caches to disk
int syncfs(int fd);
Feature Test Macro Requirements for glibc (see
_XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
causes all pending modifications to filesystem metadata and cached file
data to be written to the underlying filesystems.
but synchronizes just the filesystem containing file
referred to by the open file descriptor
returns 0 on success;
on error, it returns -1 and sets
to indicate the error.
is always successful.
can fail for at least the following reason:
is not a valid file descriptor.
first appeared in Linux 2.6.39;
library support was added to glibc in version 2.14.
POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
Since glibc 2.2.2, the Linux prototype for
is as listed above,
following the various standards.
In glibc 2.2.1 and earlier,
it was "int sync(void)", and
always returned 0.
According to the standard specification (e.g., POSIX.1-2001),
schedules the writes, but may return before the actual
writing is done. However Linux waits for I/O completions,
provide the same guarantees as fsync called on every file in
the system or filesystem respectively.
Before version 1.3.20 Linux did not wait for I/O to complete
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