chmod: Add recursive 755/644 chmod example

[mathomp4]

Might not be approved, but this is the classic 755 on all directories, 644 on all files in a tree a la: https://stackoverflow.com/questions/18817744/change-all-files-and-folders-permissions-of-a-directory-to-644-755

As I just discovered tldr, I had to try my hand at updating a page with a command I have to Google every single time.

---

• The page (if new), does not already exist in the repo.

• The page (if new), has been added to the correct platform folder:
  common/ if it's common to all platforms, linux/ if it's Linux-specific, and so on.

• The page has 8 or fewer examples.

• The PR is appropriately titled:
  <command name>: add page for new pages, or <command name>: <description of changes> for pages being edited

• The page follows the contributing guidelines

[CLAassistant]

All committers have signed the CLA.

[sbrl]

Thanks for the addition, @mathomp4! I didn't realise that you could separate multiple permissions operations with a comma like that. I'll have to remember that!

Anyway, this looks ok to me! Once we get a second opinion here we'll get to merging.

[sbrl]

I like what you've you've done here to aid in the understanding of the command! Cool 😃

[agnivade]

Can we just keep this example to "user" and remove the "group" and "others" ? I fear the description is getting a bit too long. And the "group" and "others" are already explained in earlier examples. Since, this example just introduces the -R option, I think the users can build up the go options themselves.

And also, I think we can use x instead of X. The man page does say that X is for execute/search only if the file is a directory or already has execute permission for some user (X), but I did not find any difference with x in my tests.

[mathomp4]

Actually, capital X is usually preferred because x can often do things in a way you wouldn't suspect:

• https://www.franzoni.eu/chmod-and-the-capital-x/
• https://metashell.net/index.php/2016/05/10/chmod-capital-x-gunna-give-it-to-you/
• https://prasadlinuxblog.wordpress.com/2012/05/09/the-uppercase-x-in-chmod/

Indeed, looking at that last link, this:

chmod -R u=rwX,g=rX,o=rX {{directory}}

might be a better command example. With this you are expressly saying u gets rwX and g and o get rX.

[agnivade]

I see. My only concern is earlier we use x but in this example, we use X without really explaining the difference. And if we attempt to explain the difference, the description will become huge.

Therefore, in the spirit of simplicity, I wanted to go with x.

I am open to any other suggestions you have.

[mathomp4]

Hmm. Well, I can just close the request in the sake of non-confusion.

Do you know if there is a way to provide a "custom page path" to tldr? Such that I could add my pages/common/chmod.md so my tldr sees it, but there isn't a need to get it in the official tree?

[agnivade]

We don't need to close it. I would still want the -R option to be added.

Do you know if there is a way to provide a "custom page path" to tldr?

If you use the node client, yes there is. https://github.com/tldr-pages/tldr-node-client#configuration. See last section. Though its not exactly what you want.

[mathomp4]

Well, if you want to not use X we should avoid it completely. For a recursive use perhaps we could add chmod -R g+w,o+w:

$ tree -p Dir1/
Dir1/
├── [-rw-r--r--]  file1
└── [-rw-r--r--]  file2

0 directories, 2 files
$ chmod -R g+w,o+w Dir1/
$ tree -p Dir1/
Dir1/
├── [-rw-rw-rw-]  file1
└── [-rw-rw-rw-]  file2

0 directories, 2 files

That adds write to both group and other.

[agnivade]

@sbrl - Can you take a look at this PR again ? I had some concerns due to which the PR has changed a bit. Please look at my comments here - #1651 (comment). Let me know if you are good with these.

[sbrl]

Yeah sure, @agnivade.

It still looks ok - much simpler and easy to understand :D

[sbrl]

Thanks, @mathomp4!