sync, syncfs - commit filesystem caches to disk
#include <unistd.h>
void sync(void);
int syncfs(int fd
);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
syncfs() returns 0 on success; on error, it returns -1 and sets errno
to indicate the error.
syncfs() first appeared in Linux 2.6.39; library support was added to glibc in version 2.14.
Since glibc 2.2.2, the Linux prototype for sync() is as listed above, following the various standards. In glibc 2.2.1 and earlier, it was "int sync(void)", and sync() always returned 0.
According to the standard specification (e.g., POSIX.1-2001), sync() schedules the writes, but may return before the actual writing is done. However Linux waits for I/O completions, and thus sync() or syncfs() 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 before returning.
This page is part of release 4.15 of the Linux man-pages
project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.