How can you revoke write access for all groups and named users on a file?

How can you revoke write access for all groups and named users on a file?

• A. setfacl -x group:*:r-x,user:*:r-x afile
• B. setfacl -x mask::r-x afile
• C. setfacl -m mask::r-x afile
• D. setfacl -m group:*:r-x,user:*:r-x afile

Answer: (C)

To revoke write access for all groups and named users on a file, the correct approach is to use the command that sets the access control list (ACL) mask accordingly. Utilizing the command that modifies the mask to `r-x` accomplishes this by limiting the permissions that are granted to all groups and users. When you set the mask to `r-x`, you are effectively indicating that groups and users will only have read and execute permissions on the file. This means they lose the write permission, which is the intended outcome of the action. The mask acts as a cap on what permissions can be granted to the ACL entries for groups and users, ensuring that none can have write access, even if it were granted previously. The rationale behind revoking access through the mask is that the mask limits the effective permissions for all users and groups in the ACL, allowing for granular control over file permissions without the need to edit each entry separately. This makes it a practical solution for managing file access rights at once. Other options do not achieve the desired effect of revoking write access for all groups and named users in the same straightforward manner, either modifying individual user or group permissions without addressing the access mask appropriately.

To revoke write access for all groups and named users on a file, the correct approach is to use the command that sets the access control list (ACL) mask accordingly. Utilizing the command that modifies the mask to r-x accomplishes this by limiting the permissions that are granted to all groups and users.

When you set the mask to r-x, you are effectively indicating that groups and users will only have read and execute permissions on the file. This means they lose the write permission, which is the intended outcome of the action. The mask acts as a cap on what permissions can be granted to the ACL entries for groups and users, ensuring that none can have write access, even if it were granted previously.

The rationale behind revoking access through the mask is that the mask limits the effective permissions for all users and groups in the ACL, allowing for granular control over file permissions without the need to edit each entry separately. This makes it a practical solution for managing file access rights at once.

Other options do not achieve the desired effect of revoking write access for all groups and named users in the same straightforward manner, either modifying individual user or group permissions without addressing the access mask appropriately.