RHCSA File Permissions and ACLs Questions and Answers

Question 1

A system administrator needs to set default permissions for all new files created in a specific directory, `/srv/data`, so that new files automatically inherit the group ownership of the directory and can be modified by any member of that group. Which of the following commands would accomplish this for the directory?

Accepted Answer

chmod g+s /srv/data

Answer

The `chmod g+s` command sets the Set Group ID (SGID) bit on the directory. When SGID is set on a directory, any new files or subdirectories created within it will inherit the group ownership of the parent directory, not the primary group of the user who created them. This is essential for collaborative environments where files need to be accessible by a specific team.

Question 2

A user reports they cannot delete a file they own inside the `/tmp` directory, even though the directory permissions appear to be `drwxrwxrwt`. What is the most likely reason for this issue?

Accepted Answer

The Sticky Bit is set on the `/tmp` directory, preventing users from deleting files they do not own.

Answer

The 't' at the end of the permission string `drwxrwxrwt` indicates that the sticky bit is set. When the sticky bit is set on a directory, it restricts file deletion. Only the file's owner, the directory's owner, or the root user can delete or rename files within that directory, regardless of who has write permissions on the directory itself. This is a common security measure for public directories like `/tmp`.

Question 3

Which command will grant the user `auditor` read-only access to the file `/var/log/secure` without changing the file's owner or primary group permissions?

Accepted Answer

setfacl -m u:auditor:r-- /var/log/secure

Answer

The `setfacl` command is used to set Access Control Lists (ACLs), which provide a more granular permission system than standard Unix permissions. The `-m u:auditor:r--` option modifies the ACL to specifically grant the user 'auditor' read-only (`r--`) permissions on the file, without affecting the base owner, group, or other permissions.

Question 4

A system administrator runs the command `umask 0027`. What will be the default permissions for a newly created directory?

Accepted Answer

750

Answer

The `umask` value is subtracted from the system's default permissions for new files and directories. For directories, the default is 777 (rwxrwxrwx). Subtracting the umask of 027 results in: 7-0=7, 7-2=5, 7-7=0. Therefore, the resulting permissions will be `750` (`rwxr-x---`).

Question 5

An executable file named `app.sh` has the following permissions: `-rwsr-xr--`. Which of the following statements is true?

Accepted Answer

The file will run with the privileges of the file owner.

Answer

The 's' in the owner's execute permission slot (`-rws...`) indicates that the Set User ID (SUID) bit is set. When an executable with the SUID bit is run, the process executes with the permissions of the file's owner, not the user who ran it. This is commonly used to allow regular users to run commands that require elevated privileges for specific tasks.

RHCSA Exam Practice Test

RHCSA Exam Practice Test

RHCSA File Permissions and ACLs Questions and Answers