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Re: About the `-u' option of `cp' command

>>>>> Sven Joachim <svenjoac@gmx.de> writes:
>>>>> On 2011-09-03 09:58 +0200, Rodolfo Medina wrote:


 >> Now, it happens sometimes to me that, even with `-u', `cp' will copy
 >> the file also when it isn't newer at all than the destination file,
 >> as here:

 >> $ ls -lh ing.tex /mnt/pendrive2/ing.tex 
 >> -rw-r--r-- 1 rodolfo rodolfo 163K 2011-08-31 18:44 ing.tex
 >> -rwxr-xr-x 1 rodolfo rodolfo 163K 2011-08-31 18:44 /mnt/pendrive2/ing.tex
 >> $ cp -viup ing.tex /mnt/pendrive2
 >> cp: overwrite `/mnt/pendrive2/ing.tex'?

 >> Why this, and how to avoid it?

 > Might be due to high resolution timestamps on the source filesystem,
 > but not on the target (the pendrive seems to have an FAT filesystem).
 > Use the --full-time ls option to find out.

	Please note that the filesystems of the FAT family have 2 second
	time resolution, while the usual Unix filesystems have 1 second
	resolution at worst.  Therefore, the original file may be
	18:44:55, and the destination is 18:44:54 (i. e., time gets

	Using rsync(1) and --modify-window= will probably solve the
	problem.  Consider, e. g.:

$ rsync -v -urt -O --modify-window=1 -- \
      ing.tex /mnt/pendrive2/ 

	(The -v -urt Rsync options roughly correspond to the -v -urp
	cp(1) ones.)

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