Mailinglist Archive: opensuse (878 mails)

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Re: [opensuse] copying files to USB flashdisk in alphabetical order
On 09/11/2013 06:22 PM, Istvan Gabor wrote:
2013. szeptember 10. 3:23 napon Bernhard Voelker <mail@xxxxxxxxxxxxxxxxxxx>
írta:
Unfortunately, you didn't write how the files are copied.
So my guesses out of the blue:

I don't understand what you mean "how files are copied".

I meant how the result actually looks like. You provided an
example below ...

I wrote I use cp -a --parents --target-directory=/media/disk

Maybe you add the -v option to see in which order cp(1) copies
the files.

The output is something like this:

. ./01 ./01/01.mp3 ./01/02.mp3 ./01/03.mp3 ./01/04.mp3 ./01/05.mp3
./01/06.mp3 ./01/07.mp3
./01/08.mp3 ./01/09.mp3 ./01/10.mp3 ./01/11.mp3 ./01/12.mp3 ./02 ./02/01.mp3
./02/02.mp3
./02/03.mp3 ./02/04.mp3 ./02/05.mp3 ./02/06.mp3 ./02/07.mp3 ./02/08.mp3
./02/09.mp3 ./02/10.mp3

Ah! Here is the problem .... and I described it in the next sentence:

Finally, find(1) will probably include and print the directories
first ... which will make the sorting order for cp(1) useless because
it will first copy the whole directory and then recognize that it has
to copy the files in it (which has already been done).
Did you mean this?

I think you are not right.

The above means that cp(1) first copies "." - which means the whole directory
hierarchy -, and then continues with "./01" ... which is also a directory
which has already been copied. Or in other words: all arguments after "."
are redundant and therefore do in no way influence the order of copying.
Therefore, cp(1) processes the "." directory as it always does: it just
reads the directory entries, and this is usually done on the order of their
creation.

Notice the order of creation of the directories and files:

$ mkdir 01 03 02
$ touch 01/01.mp3 02/02.mp3 03/03.mp3

To see what would be executed, I put a simple echo before cp(1):

$ find . -print0 | sort -z | xargs -0 echo cp -a --parents
--target-directory=/tmp/target -v
cp -a --parents --target-directory=/tmp/target -v . ./01 ./01/01.mp3 ./02
./02/02.mp3 ./03 ./03/03.mp3

And when executing that command, you see that first "." is processed - in the
order
of the above creation:

`./01' -> `/tmp/target/./01'
`./01/01.mp3' -> `/tmp/target/./01/01.mp3'
`./03' -> `/tmp/target/./03'
`./03/03.mp3' -> `/tmp/target/./03/03.mp3'
`./02' -> `/tmp/target/./02'
`./02/02.mp3' -> `/tmp/target/./02/02.mp3'

.... and then the rest is copied (again!) which even given you some warnings
for the directories:

cp: will not create hard link `/tmp/target/./01' to directory
`/tmp/target/./01'
`./01/01.mp3' -> `/tmp/target/./01/01.mp3'
cp: will not create hard link `/tmp/target/./02' to directory
`/tmp/target/./02'
`./02/02.mp3' -> `/tmp/target/./02/02.mp3'
cp: will not create hard link `/tmp/target/./03' to directory
`/tmp/target/./03'
`./03/03.mp3' -> `/tmp/target/./03/03.mp3'


What is important, this command always worked in my
previous systems. In openSUSE 12.2 it does not work.
(I haven tested it in 12.1).

The only reason you were satisfied with the results at that time
could be that the files have already been created in the order you
wanted ... incidentally.

Hope this helps.

Have a nice day,
Berny
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