script.sh must end up as -rwxr-x--- no matter what its current mode is. Select the TWO commands that guarantee that result.
LPIC-1 Exam 101-500, objective 104. Devices, Linux filesystems, filesystem hierarchy standard medium
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How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
The options
Choose 2.
Correct chmod 750 script.sh
Correct. An octal mode is absolute: 7 is rwx for the owner, 5 is r-x for the group, 0 is nothing for others, whatever was set before.
Correct chmod u=rwx,g=rx,o= script.sh
Correct. The = operator sets a class's permissions exactly, and `o=` with nothing after it clears the other class, so all nine bits are stated.
Not correct chmod 755 script.sh
Wrong. 755 leaves r-x for others, so the file ends up rwxr-xr-x rather than rwxr-x---.
Not correct chmod ug+x script.sh
Wrong. + only adds the execute bit; whatever read, write and other-class bits the file already carried survive, so the outcome depends on the starting mode.
Not correct chmod o-rwx script.sh
Wrong. It correctly strips the other class, but says nothing about owner and group, so it cannot guarantee rwx and r-x are present.
Why
Only absolute forms can promise a final mode: an octal argument, or symbolic clauses built with =. The relative operators + and - describe a change rather than a destination, so their result always depends on what was there before. Note also that `o=` is legal and means the empty permission set, which is how the other class is cleared symbolically.
Where this comes from
- Cited
- manual page chmod(1)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 104 and space the ones you get wrong.
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