Flush file system buffers
The sync command is used to force changed blocks to disk and update the super block.
In Linux/Unix systems, file or data processing typically involves placing data into memory buffers first, then writing to disk at an appropriate time to improve system efficiency. The sync command can be used to force data in memory buffers to be written to disk immediately. Users usually do not need to execute the sync command manually, as the system automatically performs update or bdflush operations to write buffer data to disk. Manual execution is only necessary if these operations cannot run or if the user needs to perform an abnormal shutdown.
sync (options)
-d, --data Sync only file data, not unnecessary metadata.
-f, --file-system Sync the file systems containing the specified files.
--help: Display help.
--version: Display version information.
To improve efficiency, Linux places data in a buffer before writing it to disk. Data is not committed to disk immediately. If the system restarts at this point, data loss may occur.
The sync command flushes file system buffers, ensuring data is physically written to disk and allowing buffers to be released. Therefore, it is common to run sync after writing important data to disk.
Even without manual execution, the Linux system periodically synchronizes data.