sync2
Commit filesystem caches to disk
Usage
#include <unistd.h>
void sync(void);
int syncfs(int fd);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
sync():
_XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE
syncfs():
_GNU_SOURCE
Library
Standard C library (libc, -lc)
Overview
sync() causes all pending modifications to filesystem metadata and cached file data to be written to the underlying filesystems.
syncfs() is like sync(), but synchronizes just the filesystem containing file referred to by the open file descriptor fd.
Return value
syncfs() returns 0 on success; on error, it returns -1 and sets errno to indicate the error.
Errors
sync() is always successful.
syncfs() can fail for at least the following reasons:
- EBADF
-
fd is not a valid file descriptor.
- EIO
-
An error occurred during synchronization. This error may relate to data written to any file on the filesystem, or on metadata related to the filesystem itself.
- ENOSPC
-
Disk space was exhausted while synchronizing.
- ENOSPC
EDQUOT -
Data was written to a file on NFS or another filesystem which does not allocate space at the time of a write(2) system call, and some previous write failed due to insufficient storage space.
Versions
According to the standard specification (i.e., POSIX.1), 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.
Releases
19 releases since Debian 1.1 (Buzz); the text changed 15 times.