Setting File Permissions in Linux

Project Description: Examine an existing permission of a file system and check if permissions matched the authorization that should be given. If they didn’t match, I needed to modify the permissions to the appropriate users and remove any unauthorized access.

1. Check file and directory details

In the screenshot below I used the pwd command to show my current location in the directory, then navigated to the project folders. I then used the ls -la command to list all the files and hidden files in the directory choosing the files permission for each.

2. Describe the permissions string

eg.1 drwx--x--- 2 researcher2 research_team 4096 Jan 9 02:14 drafts

The example above shows the permissions string for the drafts subfolder. It contains a 10-character string that indicates how the permission on the directory is set.

• In eg.1 above the 1^st string with the d indicates that the file type is a directory.
• The 2nd-4th characters indicate the read ( r ), write ( w ), and execute ( x ) permissions for the user.
• The 5th-7th characters indicate the read ( r ), write ( w ), and execute ( x ) permissions for the group. You will realize the 5th and 6th character has a hyphen ( - ) instead of r or w, this indicates that this permission is not granted for the group.
• The 8th-10th characters indicates the permission for the owner type called other. As you can see it only has hyphens which would indicate that the read, write, execute permission is not granted to other.

3. Change file permissions

Owner type other is not allowed to have write permission to any files. This was removed with the chmod command below.

chmod o-w project_k.txt

4. Change file permissions on a hidden file

The hidden file should not be written to by anyone, but should still be read by user and group. Hidden files are identified with a dot before the file name. In the screenshot below the hidden file is made visible with the use of the ls -la command. I used the chmod command to set user and group to have only read privileges and then removed all permissions from other.

The example above shows the hidden file .project_x.txt having the following permission set chmod u=r,g=r,o-rw .project_x.txt:

• Owner type user getting read access u=r
• Owner type group getting read access - g=r
• Owner type other loosing read and write access - o-rw

5. Change directory permissions

The only the researcher2 user was allowed access to draft directory and its content -meaning only user should have execute privileges

In the screenshot below I used the chmod command to set all permission for user, removed all permission for group and other. Then the ls -la command to display the change on permissions.

Summary

Important

This project was to show my ability to navigate the linux file system,

• to list directory files for subfolders and hidden files,
• make changes to file permissions for directories, files and hidden files.