Question

While changing permissions in an absolute manner, we explicitly set all the nine bits irrespective of the previous permissions of the file.

(a) True

(b) False

The question was asked in examination.

This intriguing question comes from Changing File Ownership and Permissions in chapter Basic File Attributes of Unix

Answer 1

The correct choice is (a) True

The explanation: The expression used by chmod in an absolute manner is a string of three octal numbers (base 8).  A set of 3 bits represent a single octal digit.

->    Read permission –4 (100 in octal)

->    Write permission –2(010 in octal)

->   Execute permission –1(001 in octal)

For each category, we add up these numbers. For example, if we have to set read and write permission then an octal number will be 110 (4+2).