modification time disorder: touch-related?

Tim Prince n8tm@aol.com
Fri Oct 29 13:38:00 GMT 2010


On 10/29/2010 12:24 AM, Oleksandr Gavenko wrote:
> On 28.10.2010 20:10, Robert McDougall wrote:
>> In running Make, I find targets being remade that shouldn't have to be
>> remade; being considered younger than the prerequisites from which
>> they've just been made.  It seems to happen especially with
>> prerequisites created by `touch`:  e.g.:
>>
>>      $ cat Makefile
>>      all : bar baz
>>
>>      bar baz : foo
>>              cp $<  $@
>>
>>      foo :
>>              touch $@
>>
>>      $ rm foo bar baz
>>      $ make
>>      touch foo
>>      cp foo bar
>>      cp foo baz
>>      $ make
>>      cp foo bar
>>      cp foo baz
>>      $ make
>>      cp foo bar
>>      cp foo baz
>>      $ make
>>      cp foo bar
>>      cp foo baz
>>      $ make
>>      cp foo bar
>>      cp foo baz
>>      $ make
>>      cp foo bar
>>      $ make
>>      make: Nothing to be done for `all'.
>>
>> Sleeping helps, but you have to sleep for quite a while; even 2 seconds
>> may not be enough:
>>
> do you build on FAT fs?
>
> It knows by lesser time precision (exactly 2 sec).
>
> Try example on NTFS.
>
If your files are on a server, of course, you need synchronization 
between the server and local system clocks, at least daily.

-- 
Tim Prince


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