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sync(8) [osx man page]

SYNC(8) 						    BSD System Manager's Manual 						   SYNC(8)

NAME
sync -- force completion of pending disk writes (flush cache) SYNOPSIS
sync DESCRIPTION
The sync utility can be called to ensure that all disk writes have been completed before the processor is halted in a way not suitably done by shutdown(8). Generally, it is preferable to use shutdown(8) to shut down the system, as they may perform additional actions such as resynchronizing the hardware clock and flushing internal caches before performing a final sync. The sync utility utilizes the sync(2) function call. SEE ALSO
fsync(2), sync(2), shutdown(8) HISTORY
A sync utility appeared in Version 4 AT&T UNIX. BSD
May 31, 1993 BSD

Check Out this Related Man Page

SYNC(2) 						     Linux Programmer's Manual							   SYNC(2)

NAME
sync - commit buffer cache to disk SYNOPSIS
#include <unistd.h> void sync(void); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): sync(): _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED DESCRIPTION
sync() first commits inodes to buffers, and then buffers to disk. ERRORS
This function is always successful. CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001. NOTES
Since 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. BUGS
According 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 ALSO
bdflush(2), fdatasync(2), fsync(2), sync(8), update(8) COLOPHON
This page is part of release 3.27 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/. Linux 2010-09-20 SYNC(2)

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