Richard Gilbert <R.Gilbert@???> wrote:
>
>Here are the relevant lines from mu Makefile:
>
> cdb_encode.pl aliases | $(CDBMAKE) tmp_aliases.cdb aliases.tmp
> cdb_encode.pl invaliases | $(CDBMAKE) tmp_invaliases.cdb invaliases.tmp
> mv invaliases.cdb invaliases.cdb.old
At this point there's an interval where the file might not be found.
> mv tmp_invaliases.cdb invaliases.cdb
> mv aliases.cdb aliases.cdb.old
> mv tmp_aliases.cdb aliases.cdb
>
>Moving the files to .old files was intended to allow any process which had
>the file open to continue, but I don't know enough about the low-level
>detail of how file handles mv commands and i-nodes behave.
You don't need to worry about that because Unix will keep a file on disk
until all the processes using it have closed it.
If you want to keep a backup copy of a file and still update it atomically,
do this:
ln file file.old
mv file.new file
Tony.
--
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http://dotat.at/
VIKING: CYCLONIC BECOMING SOUTH 5 OR 6, OCCASIONALLY 7 AT FIRST, BECOMING
VARIABLE 4 FOR A TIME. OCCASIONAL RAIN. MODERATE OR GOOD.
