Dear fellows, I'm struggling with a single script to build numpy from source in a virtual env. I want the same script to be able to be run with a normal env. So if ran from a normal env it should affect all users. If ran within a virtual env the installation should be constrained to that env. I tried setting script variables and other tricks but the script is always executed as a 'out of virtual env' user (I cannot make it aware that is running from a virtualenv), thus affecting my real working python. As the script activates other scripts I am not posting them for now (hoping that this is a simple issue). tl;dr: How can I install numpy from source and build it in a script which uses the virtual env instead of affecting the whole system? (And yes, I have looked for solutions on google but none of them worked.) Best regards,