Create install-opera.sh

Copied from ruario (https://gist.github.com/ruario) 

To install the latest stable release, issue:
sudo sh install-opera.sh --stable

To install the latest beta release, issue:
sudo sh install-opera.sh --beta

To install the latest developer release:
sudo sh install-opera.sh --developer

Alternatively you can install a specific build like so:
sudo sh install-opera.sh opera-stable_26.0.1656.32_amd64.deb

After install, you may need to re-login to your desktop environment before Opera is detected.

Note: A script to uninstall Opera is also placed on your system, to aid removing Opera later, should you wish to.

If you would like to ensure that Opera developer is automatically kept up to date, move the script to /usr/local/bin and make it executable:

sudo mv install-opera.sh /usr/local/bin/install-opera
sudo chmod +x /usr/local/bin/install-opera

You could then add the following to root's crontab:
00 18 * * 1-5 /usr/local/bin/install-opera --stable >/dev/null 2>&1

This would execute the script once a day at 18:00 (6pm), every Monday through Friday.

If you would like to schedule the script to run at different times, or would like to log the output and/or errors, read one of the many crontab guides found on the internet.

Note: You should not run this script more once per day, since we never release so frequently. Hammering Opera servers with requests could get your IP address banned and you would then receive no updates. In any case, If you ever notice that a new Opera is out and the script has not yet run, simply issue install-opera --stable manually to trigger an update right away.