Copyright (c) 1992 Drew Eckhardt (firstname.lastname@example.org), March 28, 1992 and Copyright (c) 2011 Michael Kerrisk <email@example.com> %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work i...
NAMEsync, syncfs - commit filesystem caches to disk
int syncfs(int fd);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
DESCRIPTIONsync() 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 VALUEsyncfs() returns 0 on success; on error, it returns -1 and sets errno to indicate the error.
ERRORSsync() is always successful.
syncfs() can fail for at least the following reason:
- fd is not a valid file descriptor.
VERSIONSsyncfs() first appeared in Linux 2.6.39; library support was added to glibc in version 2.14.
CONFORMING TOsync(): POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
syncfs() is Linux-specific.
NOTESSince 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.