The notation used in the above problem is called symbolic notation. Alternatively, we can use the 4-digit octal notation to specify, which is defined as follows:

• Digits from left (most significant) to right (least significant): [special bits][owner bits][group bits][world bits]
• Special bit digit = (4 if setuid) + (2 if setgid) + (1 if sticky), 0 for none of them
• All other digits = (4 if readable) + (2 if writable) + (1 if executable), 0 for none of them

For example, if no special bit is set on, the first digit should be a zero (i.e., special bits=0). For the owner bits, if the owner has read and write privileges, then the second digit should be (4 if readable) + (2 if writable) = 6 (i.e., owner bits=6). If group and world have no privilege, they will have a zero each, and the third and fourth digits should be 0 and 0, respectively (i.e., group bits=0 and world bits=0). The converted representation should then be 0600. One of the useful resources for this representation is: https://en.wikipedia.org/wiki/File_system_permissions.

Convert each of the symbolic permissions to octal notation and each of the octal permissions to symbolic notation.

1. -rw-r--r--

2. -rwxr-xr-x

3. 0400

4. 1777

5. 4755