4. Change the permission (use letters) for groups to: r w –
5. Change the permission (use numbers) for others to: r – –
6. Use again the ls command to display the updated information for both files.
7. List the groups your account belongs to:
8. Show the current user mask value
9. Change the user mask value so that users would have r – –, group would have r – – , and others would have – – – permissions.
4. To change the permission for groups to r w -, you can use the following command:
```
chmod g+rw file_name
```
This will add read and write permissions for the group.
5. To change the permission for others to r --, you can use the following command:
```
chmod o+r file_name
```
This will add read permission for others.
6. To display the updated information for both files, you can use the ls command with the -l option:
```
ls -l file_name
```
This will display the file permissions in long format.
7. To list the groups your account belongs to, you can use the following command:
```
groups
```
This will display a list of groups your account belongs to.
8. To show the current user mask value, you can use the following command:
```
umask
```
This will display the current user mask value.
9. To change the user mask value so that users would have r --, group would have r --, and others would have --, you can use the following command:
```
umask 022
```
This will set the user mask value to 022, which will give read permission to users and groups, and no permission to others.