unix: copy files across two directories without overwriting existing

Question

I have 2 folders , A and B. they are similar, but there are some files in A that are not present in B. what's the best way to copy only the new files in A into B, without changing the existing files in B?

larsks · Answer 1 · 2018-02-24T01:04:15.367

4

You can use the --update option to rsync:

cd A
rsync -a --update . ../B/

And you can do something similar using tar's --skip-old-files option:

cd A
tar -cf- . | tar -C ../B -xv --skip-old-files -f-

edited Feb 24 '18 at 01:04

answered Nov 19 '10 at 23:56

larsks

44,886
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With rsync you'd want --ignore-existing if you don't want to replace the files that have the same names but different contents. – DerfK Nov 20 '10 at 04:26
This is a pretty old question and answer, but still: I think the cpio example above is wrong. In my tests, cpio would always overwrite an older existing file in B with a newer version in A. This is not what the OP was asking for. And I don't see a way around it in the cpio manual. – Carsten Feb 23 '18 at 23:08
@Carsten, you're right! I replaced it with a tar example. – larsks Feb 24 '18 at 01:04

score 1 · Answer 2 · answered Nov 19 '10 at 23:27

1

cp with -n.

answered Nov 19 '10 at 23:27

Ignacio Vazquez-Abrams

46,517

This is there on my Ubuntu system, but man cp on my Centos 5.5 system seems to be missing it. – ehsanul Nov 19 '10 at 23:59

unix: copy files across two directories without overwriting existing

2 Answers2