I am using fedora in my home pc.I want to know that before shutting down my pc should i use sync command so that all data in the ram buffer should syncronize and i store in hard disk.
What is your opinion about sync command
Thanks
Garden

sync should be performed by the shutdown scripts. It won't hurt anything if you issue it yourself. I bind a key sequence to a suspend script that calls sync twice - just in case Depending on the file system you use, and options you may have specified, they sync at different intervals. ext3/4 by default syncs every 5 seconds.

Consult the various man pages, or have a look here http://www.kernel.org/doc/Documentation/filesystems/

Thanks for the guidance.well if we does not write sync twice before shutting down the pc what will be the affect ? I my opinion nothing.
How can i write script to add sync before shuting down the pc?

Waste of time. The shutdown sequence in the init scripts umounts all the filesystems. This forces a sync.

Hi. Sorry for “unprofessional” question (reason why I didn't create new thread for it) but if I copy huge amount of data (let's say it's half of a TB) and while copying is in progress “sync” command is executed. Can it possibly damage the result file? I mean, while copying some data will always be in cache, then it flashes and new data is moved to cache. And “sync” will try to flash all cached data and won't stop untill cache is empty while it is necessary to write to cache for next several hours (by the copy process). Can it somehow screw things up?

next time please open a new thread. in general sync cannot be dangerous at all.