No log written in Syslog and auth.log

If you want to check some errors in /var/log/syslog or /var/log/auth.log and you find both files empty, it means system is not able to write logs in both files because of permission issue or any mis configuration. Here is solution for you. 

Solution :
Reconfigure rsyslog

sudo apt-get install --reinstall rsyslog
sudo service rsyslog restart

If still it does not work, issue may be with permissions, check the owner of both files.

ls -l /var/log/syslog
ls -l /var/log/auth.log

Group and owner should be syslog & adm, if owner or group is set as root or anything else, you need to change with following commands

sudo chown syslog:adm /var/log/syslog
sudo chown syslog:adm /var/log/auth.log

Now check if it starts writing logs in both files. Still it does not work, restart the service rsyslog.

sudo service rsyslog restart

it should work now.

Ubuntu 16.04 mysql 5.6 - my.cnf changes are not taking effect

You need to check the error in syslog : /var/log/syslog

If you get something like this

kernel: [83454.649662] audit: type=1400 audit(1583063492.688:61): apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/etc/mysql/my.cnf.fallback" pid=27270 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0

Here is the solution for you.

Solution :
The root cause is a bug in the MySQL 5.6 for Ubuntu 16.04

The issue is with apparmor. It is denying access to a symlinked file.
Run following command as root.

echo '/etc/mysql/** lr,' >> /etc/apparmor.d/local/usr.sbin.mysqld

or try following with sudo user

sudo echo '/etc/mysql/** lr,' >> /etc/apparmor.d/local/usr.sbin.mysqld

But if it still does not work

sudo nano  /etc/apparmor.d/local/usr.sbin.mysqld

and add following line at the end of the file.
Now reload apparmor

sudo systemctl reload apparmor

Make some changes in my.cnf and restart mysql. Changes should take effect.

s3cmd error : /usr/bin/env: ‘python2’: No such file or directory

 Solution :
It is not able to find /usr/bin/python2 or /usr/bin/python with python2.x
To solve this install the package in debian based systems like Ubuntu.

sudo apt-get install python-minimal