student@Ubuntu:/$ ls -l total 80 drwxr-xr-x 1 root root 4096 May 9 2021 bin drwxr-xr-x 2 root root 4096 Apr 24 2018 boot drwxr-xr-x 5 root root 360 Nov 23 19:50 dev drwxr-xr-x 1 root root 4096 Nov 23 19:50 etc drwxr-xr-x 1 root root 4096 May 9 2021 home drwxr-xr-x 1 root root 4096 May 9 2021 lib drwxr-xr-x 2 root root 4096 Apr 16 2021 lib64 drwxr-xr-x 2 root root 4096 Apr 16 2021 media drwxr-xr-x 2 root root 4096 Apr 16 2021 mnt drwxr-xr-x 1 root root 4096 May 9 2021 opt dr-xr-xr-x 167 root root 0 Nov 23 19:50 proc drwx------ 1 root root 4096 May 9 2021 root drwxr-xr-x 1 root root 4096 May 9 2021 run drwxr-xr-x 1 root root 4096 May 9 2021 sbin drwxr-xr-x 2 root root 4096 Apr 16 2021 srv dr-xr-xr-x 13 root root 0 Nov 23 19:50 sys drwxrwxrwt 1 root root 4096 Nov 23 19:52 tmp drwxr-xr-x 1 root root 4096 Apr 16 2021 usr drwxr-xr-x 1 root root 4096 Apr 16 2021 var student@Ubuntu:/$ cd tmp student@Ubuntu:/tmp$ cat /var/log/auth.log cat: /var/log/auth.log: Permission denied student@Ubuntu:/tmp$ cd .. student@Ubuntu:/$ cd sys student@Ubuntu:/sys$ cat /var/log/auth.log cat: /var/log/auth.log: Permission denied student@Ubuntu:/sys$ chmod 777 sys chmod: cannot access 'sys': No such file or directory student@Ubuntu:/sys$ cd .. student@Ubuntu:/$ chmod 777 sys chmod: changing permissions of 'sys': Read-only file system student@Ubuntu:/$ chmod 777 var chmod: changing permissions of 'var': Operation not permitted1 Answer
If you want to see the content of /var/log/auth.log you just need to make use of the sudo-command:
sudo cat /var/log/auth.logwill prompt you for your password and then display the content of the file.
Don't change permissions of system files, you'd easily end up with a reinstall of your operating system.
Alternatively you could add the user to the adm-group with
sudo adduser $USER admFollowed by logout/login, groups are applied at login time.
This will make the use of the sudo-command unnecessary.
