Copying a file only when it is newer than the destination

Question

How do I copy a file in Linux only when the file being copied is newer than the version at the destination?

If the file at the destination is newer, I want the file copy to not go ahead.

score 76 · Accepted Answer · answered Sep 29 '11 at 15:30

76

Using the update option (-u) with cp should do it for you.

answered Sep 29 '11 at 15:30

Dennis

37

To save future readers some time: this question is tagged Linux. Non-GNU cp implementations (BSD, macOS, etc.) lack the `-u` option. You can use `rsync --update` instead. – user31389 Oct 21 '16 at 13:04
On FreeBSD you may want to install `coreutils` package with `pkg install coreutils`. Then, among others, you will have GNU cp under the name `gcp`. Note that there is also brew package `coreutils` which also provide `gcp`. – smbear May 28 '20 at 09:49

score 30 · Answer 2 · answered Mar 02 '15 at 09:29

30

rsync --progress -r -u /from/one/* /to/another/directory

answered Mar 02 '15 at 09:29

gnod

3

Just for completeness: `-r` means recursive operation into subdirectories and `-u` to keep newer files at destination (=update). `--progress` shows progress information during operation. – JoeGo Jan 01 '17 at 16:59
2

I strongly suggest to add the `-t` option in order to keep the timestamp from the source – gluuke Nov 27 '20 at 10:35
2

i suggest also add -p to keep the same chmod and chown rsync --progress -rutp – Kamil Dąbrowski Jan 05 '22 at 16:37

score 9 · Answer 3 · answered Sep 29 '11 at 15:27

9

You're not saying what shell you're using, so I'm going to assume ksh:

if [[ file1 -nt file2 ]]; then cp file1 file2; fi

answered Sep 29 '11 at 15:27

Kusalananda

Isn't bash most common? – Rob Sep 29 '11 at 16:58
1

@Rob, yes. This works in bash too, obviously. I just didn't have bash (or any standard Linux box) at hand when I wrote it. – Kusalananda Sep 29 '11 at 23:12

score 4 · Answer 4 · edited May 23 '17 at 12:41

4

yes|cp -ruv /from/* /to/.
yes - Answer yes to all the questions.
r - Recursive
u - update
v - Progress

works like xargs.

I don't know how to explain academically.

edited May 23 '17 at 12:41

Community

answered Nov 08 '16 at 15:03

Felippe Silvestre

1

This is kind of cryptic. Can you expand your answer to be a little more explicit, maybe include an example? Thanks. [from Review](http://superuser.com/review/low-quality-posts/592062) – fixer1234 Nov 08 '16 at 18:03
yes -> Answer yes to all the questions. – Felippe Silvestre Nov 08 '16 at 18:34

4 Answers4