update mtime file if it already exist

[crazyiop]

Please follow the guide below

• You will be asked some questions and requested to provide some information, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your issue (like that [x])
• Use Preview tab to see how your issue will actually look like

---

Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2016.12.09. If it's not read this FAQ entry and update. Issues with outdated version will be rejected.

• I've verified and I assure that I'm running youtube-dl 2016.12.09

Before submitting an issue make sure you have:

• At least skimmed through README and most notably FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)
• Site support request (request for adding support for a new site)
• Feature request (request for a new functionality)
• Question
• Other

Description of your issue, suggested solution and other information

When I donwload a file that has already been downloaded with the --no-mtime option, the mtime of the file is not updated.
The file is not downloaded again, wich is the correct behaviour, but I think the mtime should be updated (like a touch).

It would be better to have a filesystem state indepedent of the pre-existence of the file. This will make scripting more coherent and reproduceable.

use case exemple

I have a little app that get video link from users to download them. Later, another program play the videos ordered from the last submited. In the current state, if a video has already been downloaded, I have to treat that edge case to make it goes to the top of the list. With the requested change, a simple date ordering from the file will always be the correct order.

corollary

Alternatively if I first download a file with --no-mtime option and then again without it. It also makes sense to update the file date to the server upload date instead of keeping the first download date. This will solve #10038 in a more consistent manner.

[yan12125]

Sorry, but that's impossible. mtime value is from HTTP's Last-Modified header, which is a supplementary information during the download. There's no way to get server information without actual downloading.

By the way, as CDNs are popular nowadays, the same video may return different URLs each time and have different Last-Modified values. It's not a good idea to update a previous downloaded file with information from possibly different links.

[crazyiop]

ok for the corollary part then, but my main point, is still feasible : if I run a download several time with --no-mtime it should update an existing file's mtime to the current PC date.

[yan12125]

The semantic of mtime is "the last modified time of the corresponding file on the server". For your purpose, --exec is useful. You may need to write a custom post-processor to detect whether the file is already downloaded or not, see #11231 (comment)

[crazyiop]

thanks ! didn't knew of that options.
for reference --exec "touch {}" actually does the job.