How to run a LOCAL version of SAGE? 
by Nicolas T. Courtois GA18 2017

1) Install VirtualBox: 
1.A. For Windows PC: 
http://download.virtualbox.org/virtualbox/5.1.14/VirtualBox-5.1.14-112924-Win.exe
or 
https://www.virtualbox.org/wiki/Download_Old_Builds

1.B.
For Mac OSX: 
http://download.virtualbox.org/virtualbox/5.1.14/VirtualBox-5.1.14-112924-OSX.dmg

1.C. 
For Linux: 
https://www.virtualbox.org/wiki/Linux_Downloads

2) 
Obligatory extension to by run AFTER the installation:
http://download.virtualbox.org/virtualbox/5.1.14/Oracle_VM_VirtualBox_Extension_Pack-5.1.14-112924.vbox-extpack

3) 
Install SAGE machine/apppliance. 

3A. Method 1: one single OVA file. 
import an OVA file: 
for example this file, 3 Gigabytes [highly compressed]. 
http://www.mirrorservice.org/sites/www.sagemath.org/win/sage-7.4.ova
In Virtual Box go to "Import appliance". 

3.A.1. more about this, in principle not needed: https://www.maketecheasier.com/import-export-ova-files-in-virtualbox/

3.B. Method 2: better for example if you want to MOVE it from one machine to another, or CLONE it with existing SAGE worksheets!!
Copy 2 files from another PC after installation, machine definition file, on my PC called "Sage-6.9.vbox" and 
the hard drive file, on my PC called sage-6.9-disk1.vmdk, (could also be .vdi, there are several options). 
Then you just got to "Add" menu option inside the VirtualBox software and add the .vbox file and the check 
in settings/Storage if it points to the right hard drive, or it need also added manually wrt to current location on your PC. 

3C. 
More detailed instructions (not needed) for example if you wanted to do some advanced modifications, change the keyboard layout, 
make it remotely accessible etc etc. 
https://wiki.sagemath.org/SageAppliance/SageMath-7