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Re: File and directory permissions


epsilon491@xxxxxxxxxxxx wrote:
> So what you say is this: if there is an open terminal before chmod 700, then
> I can use that terminal to access "apple", but after I close terminal B,
> there is no way to access that apple directory? Neither with a shall window,
> nor with another software?

It is not about the terminal but about the way how you get to directory
/opt/experiment/apple. If you are already in it, then you do not need
to read /opt/experiment where you have no permission.

  $ mkdir experiment
  $ mkdir experiment/apple
  $ cd experiment/apple
  $ chmod a-rwx ..
  $ touch aaa
  $ touch ../../experiment/apple/x
  touch: cannot touch ‘../../experiment/apple/x’: Permission denied
  $ touch ../../experiment/apple/aaa
  touch: cannot touch ‘../../experiment/apple/aaa’: Permission denied
  $ ls -ld ../../experiment/apple
  ls: cannot access ../../experiment/apple: Permission denied
  $ ls -ld .
  drwxr-xr-x 2 thomas thomas 4096 Mar  7 12:38 .

The reason is that nobody is allowed to read ../../experiment and thus
to find ../../experiment/apple where i have permission to write.

> even in the same terminal, vi can't access the file aaa.

My vim can do on the first try.
I can store my edited file and exit vim.

But on the next try i get

  Swap file ".aaa.swp" already exists!

although "ps -ef" confirms that no vim is editing "aaa".
After removing the swap file, i can edit and store again.
Again, the file ".aaa.swp" is not removed.

So vim has a problem with the nailed up parent directory. (Maybe because
it stores its absolute path after having created it by local path ?)

> 1.) To prevent this scenario, I have to do recursive chown and chmod.

At least it would be a less tricky situation.

Equal rights for all files of a tree !
But on the other hand, some files are more equal than others ...

Have a nice day :)