Folder permission issue

Question

Kindly do not consider this as duplicate. I have created a folder as root in the directory /tmp/test/ as well as some subfolders too. I have changed the permission to read and write for all the users and groups, including the root.

$ sudo chmod -R 666 /tmp/test/

on issuing the $ ls -l /tmp/test/ ls: cannot access '/tmp/test/db': Permission denied ls: cannot access '/tmp/test/sp': Permission denied total 0 d????????? ? ? ? ? ? db d????????? ? ? ? ? ? sp I get like this, Here I am unable to create a new file or directory.

$ printf 'test' >/tmp/test/sp/test

bash: /tmp/test/sp/test: Permission denied It sounds confusing to me.

Solution 1

Directories require the executable flag, so try sudo chmod -R 776 /tmp/test.

Linux/Unix requires the execute bit in order for the user to enter a directory and access its contents, this includes listing what is inside it. Directory execute flags behave differently than a file's read flag.

Files within can be 666 however.

Solution 2

Directory permissions are slightly different than standard file permissions. Instead of read/write/execute like a file, directory permission bits are as follows:

4 (r--): The directory's contents can be shown (ls)
2 (-w-): The directory's contents can be modified (create/delete/rename)
1 (--x): The directory can be accessed with cd or similar.

Note that for directories, the w permission will not take effect unless x is also set.

In your case, your permission is set to bit 6 (rw-), which has the following effects:

• You can see the contents of the given folder
• You can not see the metadata for the folder
• You are not permitted to cd to that folder or any child folders
• You can not edit the metadata (as x is not granted)
• You are not permitted to open any file within this part of the directory tree

To fix this, simply re-add the x bit to the file:

chmod a+x /path/to/file

This is also why the default folder permission is either 0755 or 0775 while files tend to be 0644 or 0664: folders, unlike files, are effectively useless without x.

Comments

[steeldriver]

Related: Accessing files in a directory without x-permission?

[Shameerariff]

Hi @Dorian yours is doing good, but can you give me an option to prevent users on executing a script.

[Shameerariff]

I got your option, In-fact your explanation was so good. Is there is any way to prevent the user on executing any BASH scripts.

[Kaz Wolfe]

@Shameerariff This is a different question, and would best be asked as one. However, you will want to do this by denying execute to all shell scripts in that folder.

[Shameerariff]

You are correct, can you give me solution on this comment, Thank you in advance

[Delorean]

@Shameerariff To set permissions on only files and not directories, try find . -type f -exec chmod 644 {} \; in the root folder where you want to set the permissions. DO NOT RUN THIS JUST ANWHERE! It should find all your files and set read-write permissions and ignore directories.

[Shameerariff]

thanks for your kind help, But still I can create and execute a script. This folder is for the shared user, I do not want any user to create or execute any kind of script for the security reason. Kindly excuse me, I am a developer not a SysAdmin, So my approach in this case may be bit idiotic to professional sys admin.

[Delorean]

@Shameerariff No worries! And I apologise for my original answer. Please do it again but with sudo chmod -R 776 /tmp/test. This will set read-write-execute(77) for owner and group, and read-write(6) for "everyone else". Now I think the user can write a new file but not make it executable. I don't have a Linux machine to test it myself but that should work.

[Shameerariff]

Now the permission for the regular user was gone . Now it looks like ls -l /tmp/test ls: cannot access '/tmp/test/db': Permission denied ls: cannot access '/tmp/test/test': Permission denied ls: cannot access '/tmp/test/sp': Permission denied ls: cannot access '/tmp/test/test.sh': Permission denied total 0 d????????? ? ? ? ? ? db d????????? ? ? ? ? ? sp d????????? ? ? ? ? ? test -????????? ? ? ? ? ? test.sh

[Delorean]

@Shameerariff But you were able to run ls when the folder permissions were 777?

[Shameerariff]

Yes I can do anything on 777 but on 776 I am getting the problem