SYNCSection: Linux Programmer's Manual (2)
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NAMEsync - commit buffer cache to disk
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
DESCRIPTIONsync() first commits inodes to buffers, and then buffers to disk.
ERRORSThis function is always successful.
CONFORMING TOSVr4, 4.3BSD, POSIX.1-2001.
NOTESSince glibc 2.2.2 the Linux prototype is as listed above, following the various standards. In libc4, libc5, and glibc up to 2.2.1 it was "int sync(void)", and sync() always returned 0.
BUGSAccording to the standard specification (e.g., POSIX.1-2001), sync() schedules the writes, but may return before the actual writing is done. However, since version 1.3.20 Linux does actually wait. (This still does not guarantee data integrity: modern disks have large caches.)
SEE ALSObdflush(2), fdatasync(2), fsync(2), sync(8), update(8)
COLOPHONThis page is part of release 3.21 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.