Challenge 05 - Standard file permissions - Coach’s Guide

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Notes & Guidance

1. As a regular user (student), create a directory ~/permissions.

student@vm01:~$ mkdir ~/permissions

1. Create a file called myfile.txt under ~permissions.

student@vm01:~$ touch ~/permissions/myfile.txt

1. List the properties of the file /var/log/waagent.log. Then copy this file to your permissions directory. Who is the new owner of this file now?

student@vm01:~$ ls -l /var/log/waagent.log

-rw-r--r-- 1 root root 192274 Apr 11 17:07 /var/log/waagent.log

student@vm01:~$ cp /var/log/waagent.log ~/permissions/

student@vm01:~$ ls -ls ~/permissions/

-rw-r--r-- 1 student student      0 Apr  8 14:55 myfile.txt
-rw-r--r-- 1 student student 195022 Apr 11 19:51 waagent.log

1. As root, create a file called rootfile.txt in the /home/student/permissions directory.

student@vm01:~$ sudo su

root@vm01:/# touch /home/student/permissions/rootfile

1. As regular user (student), look at who owns this file created by root.

root@vm01:/# exit

student@vm01:~$ ls -l ~/permissions

total 4
-rw-rw-r-- 1 student student   0 Apr  8 14:55 myfile.txt
-rw-r--r-- 1 root      root        0 Apr  8 14:58 rootfile
-rw-r--r-- 1 student student 195022 Apr 11 19:51 waagent.log

1. Change the ownership of all files in /home/student/permissions to yourself (student).

student@vm01:~$ chown student ~/permissions/*

chown: changing ownership of '/home/student/permissions/rootfile': Operation not permitted

Note you cannot become owner of the file that belongs to root.

1. Make sure you (student) have all rights to files within ~, and others can only read

student@vm01:~$ find ~ -type d -exec chmod 755 {} \;

student@vm01:~$ find ~ -type f -exec chmod 644 {} \;

chmod: changing permissions of '/home/student/permissions/rootfile': Operation not permitted

Note you cannot change permissions of the file that belongs to root.