How to grant full access to any new folders/files/subfolders created in a specific folder?

Question

I have granted full access to a folder as follows:

sudo chmod 777 -R /media/sharedfolder

However when a new subfolder is created by User A, that subfolder is not accessible by other users. How can I automatically grant full access to any new folders/files/subfolder that are created in this folder?

I'm running Ubuntu 20.04.6 LTS

Answer 1

You can set the default ACLs^{(file access control lists)} specific to this particular directory like so:

for i in u g o
  do
    setfacl --default --modify "$i"::7 /media/sharedfolder
    done

... where u g o are user, group and other, the skipped empty field in :: means any user/group, the 7 is a bit-wise combination of read (4), write (2), and execute (1) which, in this case, is equivalent to rwx which can alternatively be used instead and /media/sharedfolder is the desired target directory.

The target directory and any sub-directories/files to be created under it from now on will be set to those permissions by default.

However, on files, the execution bit is not set by default (not even with umask 0000) ... It'll need to be set manually after the files have been created if/when it's required ... Read and write bits, however, can be set by the default permissions.

Answer 2

The mask of any file/directories created by a user is defined by the users umask. The umask is generally set in the users .bashrc or via /etc/login.def system wide.

The standard umask in Ubuntu is 022 - this results in new files 644 and directories as 755.

***NOTE Only use 777 if you are sure you want everyone to have permission to view, and run files within this directory, using 777 in the wrong place, is a major secuirty risk.

If you really really want User A to create directories with a 777, then modify User A umask in .bashrc in the Users home directory.

Alternatively, you could create a little script eg:

file: /usr/bin/mkmediadir

#!/bin/bash
mkdir $1
chmod 777 $1 

set the script permissions to allow executable.

chmod +x /usr/bin/mkmediadir

now all User A needs to do when you want to create a new directory in /media/sharedfolder is run mkmediadir and the permissions will be set. This would remove the risk that User A creates a sensative directory with open permissions in error.