> For the complete documentation index, see [llms.txt](https://alicenab.gitbook.io/linux/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://alicenab.gitbook.io/linux/redhat/redhat-administration-2-rh134/chapter-4.md).

# Chapter 4

Controlling access to files with ACLS

#### `getfacl` Command

* **`getfacl`**: Displays the Access Control List (ACL) for a file or directory.

  ```bash
  bashCopy codegetfacl file
  ```

#### `setfacl` Command

* **`setfacl`**: Modifies the ACL of a file or directory.

  ```bash
  bashCopy codesetfacl options file
  ```

#### `setfacl` Examples

1. **Set ACL for a user with read and execute permissions if the file is a directory (otherwise read-only):**

   ```bash
   bashCopy codesetfacl -m u:name:rX file
   ```

   * `u:name`: Specify the user.
   * `rX`: Read and execute permission (execute only if the file is a directory).
2. **Set ACL for a group with read and write permissions:**

   ```bash
   bashCopy codesetfacl -m g:name:rw file
   ```

   * `g:name`: Specify the group.
   * `rw`: Read and write permissions.
3. **Remove all permissions for others:**

   ```bash
   bashCopy codesetfacl -m o::- file
   ```

   * `o::-`: No permissions for others.
4. **Set multiple ACL entries for user, group, and others:**

   ```bash
   bashCopy codesetfacl -m u::rwx,g:consultants:rX,o::- file
   ```

   * `u::rwx`: User has read, write, and execute permissions.
   * `g:consultants:rX`: Group 'consultants' has read and execute permissions.
   * `o::-`: No permissions for others.
5. **Copy ACLs from one file to another:**

   ```bash
   bashCopy codegetfacl file-A | setfacl --set-file=- file-B
   ```

   * `getfacl file-A`: Get ACL of `file-A`.
   * `setfacl --set-file=- file-B`: Apply the ACL of `file-A` to `file-B`.
6. **Set the mask for the ACL:**

   ```bash
   bashCopy codesetfacl -m m::r file
   ```

   * `m::r`: Set the mask to read-only.
7. **Recursively set ACL for a user with read and execute permissions on a directory and its contents:**

   ```bash
   bashCopy codesetfacl -R -m u:name:rX directory
   ```

   * `-R`: Recursive.
   * `u:name:rX`: User has read and execute permissions.
8. **Remove ACL entries for a user and a group:**

   ```bash
   bashCopy codesetfacl -x u:name,g:name file
   ```

   * `-x u:name,g:name`: Remove ACL entries for the specified user and group.
9. **Remove all ACL entries:**

   ```bash
   bashCopy codesetfacl -b file
   ```

   * `-b`: Remove all ACL entries.
10. **Set default ACL for a user with read and execute permissions on a directory:**

    ```bash
    bashCopy codesetfacl -m d:u:name:rx directory
    ```

    * `d:u:name:rx`: Default ACL for the specified user with read and execute permissions.
11. **Remove default ACL for a user:**

    ```bash
    bashCopy codesetfacl -x d:u:name directory
    ```

    * `-x d:u:name`: Remove default ACL for the specified user.
12. **Recursively set ACL for a group with read, write, and execute permissions on a directory and its contents:**

    ```bash
    bashCopy codesetfacl -Rm g:consultants:rwX /shares/content
    ```

    * `-Rm`: Recursive with the mask.
    * `g:consultants:rwX`: Group 'consultants' has read, write, and execute permissions.
13. **Recursively remove ACL for a user:**

    ```bash
    bashCopy codesetfacl -Rm u:consultant1:- /shares/content
    ```

    * `u:consultant1:-`: Remove all permissions for 'consultant1'.
14. **Set default ACL for a group with read, write, and execute permissions on a directory:**

    ```bash
    bashCopy codesetfacl -m d:g:consultants:rwx /shares/content
    ```

    * `d:g:consultants:rwx`: Default ACL for the group 'consultants' with full permissions.
15. **Set default ACL for a user with no permissions on a directory:**

    ```bash
    bashCopy codesetfacl -m d:u:consultant1:- /shares/content
    ```

    * `d:u:consultant1:-`: Default ACL for 'consultant1' with no permissions.
16. **Recursively set ACL for a group with read, write, and execute permissions on a directory and its contents:**

    ```bash
    bashCopy codesetfacl -Rm g:contractors:rwX /shares/cases
    ```

    * `g:contractors:rwX`: Group 'contractors' has read, write, and execute permissions.
17. **Recursively set ACL for a user with read and execute permissions on a directory and its contents:**

    ```bash
    bashCopy codesetfacl -Rm u:contractor3:rX /shares/cases
    ```

    * `u:contractor3:rX`: User 'contractor3' has read and execute permissions.
18. **Set default ACL for a group with read, write, and execute permissions on a directory:**

    ```bash
    bashCopy codesetfacl -m d:g:contractors:rwx /shares/cases
    ```

    * `d:g:contractors:rwx`: Default ACL for 'contractors' with full permissions.
19. **Set default ACL for a user with read and execute permissions on a directory:**

    ```bash
    bashCopy codesetfacl -m d:u:contractor3:rx /shares/cases
    ```

    * `d:u:contractor3:rx`: Default ACL for 'contractor3' with read and execute permissions