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sync - Unix, Linux Command
sync - synchronize data on disk with memory
sync [--help] [--version]
sync writes any data buffered in memory out to disk. This can
include (but is not limited to) modified superblocks, modified inodes,
and delayed reads and writes. This must be implemented by the kernel;
sync program does nothing but exercise the
The kernel keeps data in memory to avoid doing (relatively slow) disk
reads and writes. This improves performance, but if the computer
crashes, data may be lost or the filesystem corrupted as a result.
sync ensures that everything in memory is written to disk.
sync should be called before the processor is halted in an unusual manner
(e.g., before causing a kernel panic when debugging new kernel code).
In general, the processor should be halted using the
commands, which will attempt to put the system in a quiescent state
(Various implementations of these commands exist; consult your
documentation; on some systems one should not call
GNU STANDARD OPTIONS
Print a usage message on standard output and exit successfully.
Print version information on standard output, then exit successfully.
Terminate option list.
The variables LANG, LC_ALL, LC_CTYPE, and LC_MESSAGES have the
sync is only guaranteed to schedule the dirty blocks for writing; it can
actually take a short time before all the blocks are finally written.
commands take this into account by sleeping for a few seconds after
This page describes
sync as found in the file utils-4.0 package;
other versions may differ slightly.