Now, if you're going to use Idle and you're going to use virtualenv, 0:00 I need to show you a special thing for launching Idle inside of your virtualenv. 0:03 Normally, launching Idle would not let you use your virtualenv installed packages. 0:09 But if we launch Idle from inside of our virtualenv, 0:14 python -m idlelib, then we have access to our libraries. 0:19 Like here I can say import flasks, no problems. 0:26 So if your virtualenv gets screwed up and you need to start over, what do you do? 0:30 I said in the last video that they're disposable, right? 0:35 We deleted it, we made it again, and I mentioned installing packages. 0:38 So first of all, let's see what we have installed. 0:43 So we'll do pip freeze and we have flask, it's dangerous, 0:45 Jinja2,MarkupSafe and Werkzeug. 0:50 Which I apologize to all of my German speaking students. 0:53 I know I said that wrong. 0:57 If you can send me a better pronunciation of it, I would love it. 0:58 This givesa list of all the packages that we have installed and then we have this 1:01 double equals and the exact version of the package that we have installed, 1:06 so we have exactly Flask 0.10.1, not 0.10.2 or 0.10.0. 1:12 So we can copy this. 1:18 Alright, we can [SOUND] copy that. 1:21 Or we can be lazy. 1:23 We copy it, we paste it into a new file, right? 1:25 Or we can be lazy and let the computer do it for us. 1:27 So if we do pip freeze and then we do a greater than sign and 1:31 then the name of a file, which we're gonna do requirements.txt. 1:34 And now if I cat, 1:40 requirements requirements.txt which cat just makes it print. 1:42 It's got the same thing in there, so the greater than tells the computer to put 1:44 the output of pip freeze into a file named requirements.txt. 1:49 Now this file name isn't a requirement, but it is a very common practice to use 1:53 that name and some third parties services like Kiroku kind of expect that name. 1:58 Okay, so let's make sure this works. 2:03 So I should be able to get out of here, deactivate and 2:06 I should be able to rm -rf fb. 2:10 So I do not have fb installed. 2:13 And then, I should be able to make a new one. 2:16 So let's go up here, let's find my thing I did, there it is, python3 -m venv fb. 2:20 Alright and then, source fb/bin/activate. 2:27 Okay, we are back to this. 2:33 And if we do pip freeze, there is nothing installed yet 2:34 because I haven't installed things yet. 2:37 Let's install things. 2:39 So we can do pip install, and normally here we would type in like, flask, right? 2:40 Let's not do that, though. 2:46 -r says "Hey, go read this file". 2:47 And we're gonna read requirements.txt. 2:51 So press enter, and it installs everything. 2:54 And if we now do pip freeze, there is our normal list of all of our stuff. 2:58 Everything's installed again, that's awesome. 3:03 Congratulations, you have a solid local Python installation you can use to follow 3:07 along with the courses here on Treehouse or just for experimenting with code, or 3:12 writing software for clients of your own, or a developer job. 3:16 I'm sure you'll do so much with these new tools. 3:20