What does chmod 789 represent?

Question

This was one of my exam questions, I wanted to know what does it represent?

The question was:

What is the equivalent of running chmod 789 a.txt?

• chmod u=rw,g+w,o-x a.txt

• chmod a=rwx,u+s a.txt

• chmod u=rwx,g=rwx,o=rx a.txt

• other

Answer 1

8 and 9 are not valid. Unfortunately, your list of options does not clearly have a 'not valid' option. Though, all you had to do was try this in unix to find your answer.