Linux how to copy but not overwrite?

Question

I want to cp a directory but I do not want to overwrite any existing files even it they are older than the copied files. And I want to do it completely noninteractive as this will be a part of a Crontab Bash script. Any ideas?

https://unix.stackexchange.com/questions/67539/how-to-rsync-only-new-files — n611x007, Jun 26 '15 at 12:26
[SuperUser - Copy files in linux but avoid the copy if files do exist in destination](https://superuser.com/questions/118781/copy-files-in-linux-avoid-the-copy-if-files-do-exist-in-destination) — cssyphus, Aug 13 '22 at 19:23
**TL;DR:** For files, `cp -n copyFile pasteFile`, but for directories, `cp -r -n copyDir pasteDir` — Andrew, Sep 25 '22 at 23:37

score 779 · Accepted Answer · edited May 26 '16 at 18:56

779

Taken from the man page:

-n, --no-clobber
              do not overwrite an existing file (overrides a previous -i option)

Example:

cp -n myoldfile.txt mycopiedfile.txt

edited May 26 '16 at 18:56

Neal

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answered Feb 22 '12 at 10:12

hovanessyan

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Note, this will exit with an error if the file exists. To exit with success, try ```cp -n source.txt destination.txt || true``` – galenandrew Apr 01 '16 at 16:38
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@galenandrew `cp -n` does not exit with error if the file exists on Ubuntu 12.04. – amit kumar Aug 29 '16 at 09:47
@galenandrew Confirmed. Thank you. My project wasn't building in Xcode after adding a run script to my target. – Ruiz Apr 17 '17 at 20:30
@AaronFranke looks like it does. – Boris Verkhovskiy Aug 26 '19 at 06:07
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Even with Ubuntu 18.04, the behavior is the same, that when the file exists, the command exit without erro, that is, an no op! This is dangerous! – Yu Shen Jul 21 '20 at 18:44
`cp -n source.txt dest.txt || test -f dest.txt` won't ignore error if `source.txt` and `dest.txt` are missing – Jook Sep 24 '20 at 10:50
FWIW, I have noticed that a *needed* `-n` exits `1` on Arch, but exits `0` on Manjaro. So, the behavior seems to be connected to the stack, similarly to how `cp -i` is often a link for `cp` in `.bashrc` on desktop distros. I only found this because I didn't stop at testing on my desktop, but on the actual machine it would be used—always test on your identical setup, not merely a distro related to the stack. – Jesse Apr 04 '23 at 09:31
And, it would work for `cp -n myfolder/* newfolder/` with identical behavior, and will not break if encountering an existing file where the `-n` is needed. – Jesse Apr 04 '23 at 09:33
always read your man page - that's the main takeaway from this answer at least IMO – hovanessyan Apr 04 '23 at 15:07

score 137 · Answer 2 · edited Aug 17 '18 at 13:51

137

Consider using rsync.

rsync -a -v --ignore-existing src dst

As per comments rsync -a -v src dst is not correct because it will update existing files.

edited Aug 17 '18 at 13:51

ndemou

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answered Aug 16 '14 at 17:45

Hans Ginzel

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You want to add the `--ignore-existing` flag to prevent existing files from being overwritten. – Uyghur Lives Matter Aug 16 '14 at 18:22
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Complete command `rsync -a -v --ignore-existing ` is indeed the correct answer, instead of `cp -u`above. – Whitebird May 18 '15 at 09:04
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If a previous copy was interrupted and only a truncated file copied, I'm sure cp -u won't re-copy it... but will rsync, with --ignore-existing? Probably not either... so that makes them perfectly equivalent, right? – dagelf Dec 16 '17 at 16:40
rsync keeps the file timestamp while cp uses the current time (in my experience) – Stefan Dec 27 '17 at 16:27
You can use `--preserve=timestamps` with `cp` to preserve the timestamps. – Wilson F Aug 10 '18 at 22:33
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some servers just has no rsync – mebada Apr 04 '19 at 10:59
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absolutely. I don't want to install `rsync` into my docker container, just to do a copy! I can't imagine why we should use a cannon when a BB gun will suffice. – Auspex Jun 04 '19 at 13:01

score 63 · Answer 3 · answered Feb 22 '12 at 10:11

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cp -n

Is what you want. See the man page.

answered Feb 22 '12 at 10:11

bucko

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The man page: `-n Do not overwrite an existing file. (The -n option overrides any previous -f or -i options.)` – rebane2001 Dec 16 '21 at 13:00

score 39 · Answer 4 · answered Nov 15 '13 at 09:20

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This will work on RedHat:

false | cp -i source destination 2>/dev/null

Updating and not overwriting is something different.

answered Nov 15 '13 at 09:20

ceving

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What does `false` do here? – Frozen Flame Jun 14 '14 at 12:35
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@FrozenFlame Answers `-i` questions. – ceving Jun 14 '14 at 17:35
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Obviously, this command won't work if you'll try to copy more than ARG_MAX files. To work-around this case, check this [link](http://unix.stackexchange.com/a/110285). – mginius Oct 27 '15 at 15:55
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Also obviously, this command won't work if the earth crashes into the sun. – ceving Jan 27 '20 at 08:50
@ceving I think you'll find that `oh-my-zsh` has an alias for that use-case. – Michael Paulukonis Nov 06 '20 at 16:45

Grim... · Answer 5 · 2014-02-19T15:21:28.660

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For people that find that don't have an 'n' option (like me on RedHat) you can use cp -u to only write the file if the source is newer than the existing one (or there isn't an existing one).

[edit] As mentioned in the comments, this will overwrite older files, so isn't exactly what the OP wanted. Use ceving's answer for that.

edited Feb 19 '14 at 15:21

answered Jun 04 '13 at 16:45

Grim...

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OP asked not to overwrite existing files **even if they are older than copied files**, so `-u` doesn't actually fit purpose. – Andrew Lott Feb 19 '14 at 10:39
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Goodness, you're absolutely right. I'm surprised it took so long for anyone to notice. – Grim... Feb 19 '14 at 15:20
It might not be what the OP asked for, but it's exactly what I needed for my Uberspace (Centos 7). Thanks! – Thomas Praxl Dec 11 '19 at 21:39
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I'm glad six years ago me could help :-D – Grim... Dec 13 '19 at 08:55

Kamil Kiełczewski · Answer 6 · 2019-06-04T13:08:43.447

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Alpine linux: Below answer is only for case of single file: in alpine cp -n not working (and false | cp -i ... too) so solution working in my case that I found is:

if [ ! -f env.js ]; then cp env.example.js env.js; fi

In above example if env.js file not exists then we copy env.example.js to env.js.

edited Jun 04 '19 at 13:08

answered May 11 '17 at 19:55

Kamil Kiełczewski

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score 9 · Answer 7 · answered Jul 22 '19 at 20:47

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Some version of cp do not have the --no-clobber option. In that case:

  echo n | cp -vipr src/* dst

answered Jul 22 '19 at 20:47

Shōgun8

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Super good suggestion. I lost a lot of time debugging scripts until I realised the --no-clobber option is not available everywhere. Thanks! – Raz Aug 25 '20 at 03:54
Work like a charm! – Steven Lee Jun 08 '21 at 03:23

score -3 · Answer 8 · answered Aug 27 '20 at 04:24

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This works for me yes n | cp -i src dest

answered Aug 27 '20 at 04:24

CipherXEN

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It is much more effective to use the '--no-clobber' instead of forcing interactive copy with negative input. – dash-o Aug 27 '20 at 05:25

Linux how to copy but not overwrite?

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