Change file permissions for names starting with 'emp' and ending with 1, 2, or 3 so that the user (owner) gains execute permission: which chmod command is appropriate?

Introduction / Context:Managing permissions in Unix/Linux often involves applying changes to sets of files selected by shell globs. Understanding chmod symbolic modes and bracket patterns ensures precise, minimal changes to the correct targets without over-permissive settings.

Given Data / Assumptions:

• Target files are named 'emp1', 'emp2', or 'emp3' (i.e., start with 'emp' and end with 1–3).
• Goal: add execute permission for the user (owner) only.
• We prefer symbolic mode for clarity (u+x).

Concept / Approach:

The shell glob emp[1-3] matches exactly the names ending in 1, 2, or 3. The chmod symbolic form u+x adds execute permission to the owner without altering group or others. Combining them gives chmod u+x emp[1-3], which is specific and safe.

Step-by-Step Solution:

Verification / Alternative check:

Run stat emp1 before and after to confirm mode changes only for the user execute bit. If scripts are in these files, test execution with ./emp1 (assuming proper shebang and path).

Why Other Options Are Wrong:

• chmod 777 emp*: over-permissive, affects many files, not just 1–3, and changes group/others unnecessarily.
• chmod u+r ??? emp: malformed; adds read, not execute; and incorrect glob usage.
• chmod 222 emp?: sets write-only for user/group/others; also matches any single extra character, not just 1–3.
• None of the above: incorrect since the correct command is listed.

Common Pitfalls:

• Using * and modifying too many files.
• Confusing symbolic and octal modes.

Final Answer:

chmod u+x emp[1-3].