Refer to the exhibit. A user tries to execute a script on a mounted filesystem but gets a permission denied error. The script has execute permissions. What is the most likely cause?
The `noexec` mount option instructs the kernel to refuse execution of any binary or script residing on that filesystem, regardless of the file's own execute permission bits. Since the script already has execute permissions, the mount-level restriction is the only remaining cause of the permission denied error.
Why this answer
The 'noexec' mount option prevents execution of any binary or script on the filesystem, regardless of file permissions. Even if the script has execute permissions set, the kernel will refuse to execute it when the filesystem is mounted with 'noexec'. This is a common security measure on filesystems like /tmp or /home to prevent unauthorized code execution.
Exam trap
The trap here is that candidates often assume 'permission denied' always means incorrect file permissions, but the LPIC-1 exam tests the understanding that mount options like 'noexec' can override file-level permissions and cause execution failures.
How to eliminate wrong answers
Option A is wrong because the question explicitly states that the script has execute permissions, so the script is executable for the user. Option B is wrong because read permission is not required to execute a script; execute permission alone is sufficient for execution (though the interpreter needs read access to the script file). Option D is wrong because a full filesystem would cause write failures, not a 'permission denied' error when trying to execute a script.