chmod practice (symbolic mode example) For a file named note, which command removes execute permission from the user (owner) and grants read permission to the group and others?
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Achmod u-x, go+r note
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Bchmod go+r, u+x note
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Cchmod g-x, uo+r note
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Dchmod go+x, u-x note
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ENone of the above
Answer
Correct Answer: chmod u-x, go+r note
Explanation
Introduction / Context:Symbolic chmod expressions allow precise, readable permission changes. Administrators frequently need to revoke execute rights from owners while providing read access to collaborators, making a combined symbolic expression convenient and auditable in scripts and documentation.
Given Data / Assumptions:
- Target file is note.
- Desired result: user loses x; group gains r; others gain r.
- Order of symbolic operations can be combined with commas in a single command.
Concept / Approach:Use classes u (user), g (group), o (others) and operators + (add), - (remove). Multiple clauses separated by commas are applied left-to-right. Here we want to remove x for u and add r for g and o. The syntax can be expressed as one command against the file note.
Step-by-Step Solution:Remove user execute bit: chmod u-x noteAdd read for group and others: chmod go+r noteCombine: chmod u-x,go+r noteVerify: ls -l note shows expected r bits and no x for user.
Verification / Alternative check:Numeric equivalent depends on prior bits; to set absolutely, use = with known baseline (e.g., chmod u=rw,g=r,o=r note to force 644). Symbolic modification is safer when you only intend relative changes.
Why Other Options Are Wrong:Option B adds user execute (u+x), opposite of requirement.Option C removes group execute (g-x) but does not address user execute; also grants read to user and others (uo+r) inexactly.Option D adds execute to group and others (go+x), contrary to the brief.
Common Pitfalls:
- Mistyping commas or spaces causing the shell to parse separate commands incorrectly.
- Confusing class letters; u is owner, not user accounts in general.
- Forgetting to quote filenames containing spaces.
Final Answer:chmod u-x, go+r note