There are some things done in some installations but waiting for you to be done on another. Here I will tell you some of them (feel free to comment this page to insert new ones).
Just insert your timezone name into /etc/timezone, like this (as user)
echo “Europe/Madrid” | sudo tee /etc/timezone
echo “Europe/Madrid” > /etc/timezone
In debian based distributions you can use:
sudo dpkg-reconfigure tzdata
If you are not en_US (commonly installed in virtual servers by default), you may want to change it, so, you may (in a Debian based system…):
$ sudo locale-gen es_ES.UTF-8
$ sudo dpkg-reconfigure locales
To add es_ES with UTF-8 encoding.