Question

Suppose that you are a superuser on a Linux system, and there is a file “/home/bob/foo”, which is owned by an ordinary user Bob. You need to give a permission to read this file to an ordinary user Alice, but no one else (of course, you as superuser will be able to read it too). Explain how you will do it. Note: You do not have to provide specific commands, just a short description will suffice.

Answer 1

As given, In Linux system there is a file “/home/bob/foo”, which is owned by an ordinary user Bob. We need to give read permissions to Alice also, but not anyone else. To solve this, first, we need to create a group and need to add users Bob and Alice. Then we need to change the file permissions so that the newly created group can read that file.

• Let us create a group first,

groupadd GROUP1

• Then add Aice in that group,

usermod -a -G GROUP1 Alice

• Change the file permission so that Alice and the super owner can read that document(Not even Bob).

chgrp Alice /home/bob/foo

chmod 400  /home/bob/foo

As we have changed group ownership also, Bob can not access this file.