Granting execute permission (owner only): Which chmod command gives the file owner execute permission on the file 'note' (without changing other existing permissions)?

Introduction / Context:
Selective permission changes are common when turning a script into an executable. The chmod command supports symbolic modes that add (+), remove (-), or set (=) permissions for user (u), group (g), and others (o) without affecting unrelated bits.

Given Data / Assumptions:

• Target file: note.
• Goal: add execute permission for the owner only.
• Other existing permissions should remain unchanged.

Concept / Approach:

Use symbolic mode with the user class: u+x means “add execute for user.” It leaves group and others untouched. Verification is done via ls -l, which shows permission triplets as rwx.

Step-by-Step Solution:

Verification / Alternative check:

Execute the file (./note) if it is a script or binary. If permission denied appears, re-check owner and execute bit, and ensure the filesystem is mounted with exec allowed.

Why Other Options Are Wrong:

a: Grants execute to group, not owner.

b: Adds write, not execute, to owner.

d: Grants execute to user, group, and others, broader than requested.

e: Not applicable; option c is correct.

Common Pitfalls:

Accidentally overexposing a file with ugo+x; forgetting executable shebang for scripts; modifying permissions on a non-executable mount.

Final Answer:

chmod u+x note