1 00:00:00,480 --> 00:00:01,560 Presenter: Now, the first thing we're gonna do 2 00:00:01,560 --> 00:00:03,600 is open up Terminal. 3 00:00:03,600 --> 00:00:07,890 And inside Terminal, we're gonna navigate to our desktop. 4 00:00:07,890 --> 00:00:10,500 So if you're not familiar with the command line 5 00:00:10,500 --> 00:00:13,860 and you haven't watched the module on the command line, 6 00:00:13,860 --> 00:00:16,560 then I recommend you to take a look at it now, 7 00:00:16,560 --> 00:00:18,300 because we're gonna be using a lot of the commands 8 00:00:18,300 --> 00:00:20,670 to create directories and navigate around. 9 00:00:20,670 --> 00:00:22,500 So if you're not yet familiar, 10 00:00:22,500 --> 00:00:24,750 then it's a good time to take a look at that. 11 00:00:25,890 --> 00:00:26,880 The first thing I'm gonna do 12 00:00:26,880 --> 00:00:29,350 is I'm going to CD into my desktop 13 00:00:31,260 --> 00:00:35,553 and here I'm going to create a new directory called Story. 14 00:00:36,870 --> 00:00:41,280 Then I'm going to cd into this Story directory. 15 00:00:41,280 --> 00:00:43,110 And if I show you with ls, 16 00:00:43,110 --> 00:00:45,150 you can see that it's completely empty. 17 00:00:45,150 --> 00:00:49,590 And similarly, inside Finder, I can show you the same thing. 18 00:00:49,590 --> 00:00:53,130 Let's go ahead and create some text files. 19 00:00:53,130 --> 00:00:57,840 I'm gonna use touch to create a file called chapter1.txt. 20 00:00:57,840 --> 00:01:01,087 And then I'm gonna open chapter1.txt. 21 00:01:03,630 --> 00:01:06,480 So let's go ahead and open chapter 1 22 00:01:06,480 --> 00:01:09,033 and let's write something inside, shall we? 23 00:01:12,750 --> 00:01:15,180 Okay, so there's my masterpiece done. 24 00:01:15,180 --> 00:01:17,883 I'm gonna go ahead and hit Save and I'm gonna quit. 25 00:01:19,320 --> 00:01:22,890 So that was our first chapter done. 26 00:01:22,890 --> 00:01:27,510 Now, let's create a Git local repository 27 00:01:27,510 --> 00:01:30,600 and start tracking some of these file changes. 28 00:01:30,600 --> 00:01:33,570 To initialize Git, we simply write git init. 29 00:01:35,220 --> 00:01:39,210 And as you can see, it's initialized an empty Git repository 30 00:01:39,210 --> 00:01:41,370 inside the Story directory. 31 00:01:41,370 --> 00:01:43,260 Now, if you have a look inside Finder, 32 00:01:43,260 --> 00:01:46,230 you actually can't see this .git at all. 33 00:01:46,230 --> 00:01:48,963 But as we learned before, if you use ls -a, 34 00:01:49,830 --> 00:01:51,510 you can see all the hidden files 35 00:01:51,510 --> 00:01:54,120 and you can see that .git is right there 36 00:01:54,120 --> 00:01:57,210 and it's going to be used to track all your changes, 37 00:01:57,210 --> 00:02:01,200 to commit your changes, and to perform version control. 38 00:02:01,200 --> 00:02:04,230 So we're currently inside the Story directory 39 00:02:04,230 --> 00:02:06,990 and you can also call this the working directory. 40 00:02:06,990 --> 00:02:08,580 So as I mentioned before, 41 00:02:08,580 --> 00:02:11,250 using Git and learning about version control, 42 00:02:11,250 --> 00:02:15,420 it comes with some of its own terminology and language. 43 00:02:15,420 --> 00:02:16,770 So I'm gonna try and simplify 44 00:02:16,770 --> 00:02:19,020 a lot of these terms that you'll come across 45 00:02:19,020 --> 00:02:21,150 just so that we can all be on the same page 46 00:02:21,150 --> 00:02:24,150 and we all understand what's going on. 47 00:02:24,150 --> 00:02:27,480 Currently, we are inside the working directory, 48 00:02:27,480 --> 00:02:29,700 which is the Story directory. 49 00:02:29,700 --> 00:02:34,700 And here in order to start tracking the changes of my files, 50 00:02:35,460 --> 00:02:40,410 for example, chapter1.txt, then I need to add this file 51 00:02:40,410 --> 00:02:43,470 to what's called a staging area. 52 00:02:43,470 --> 00:02:47,250 And that is basically a intermediate place 53 00:02:47,250 --> 00:02:49,830 where you can pick and choose which files 54 00:02:49,830 --> 00:02:53,970 inside your working directory that you want to commit. 55 00:02:53,970 --> 00:02:57,120 So to see what's currently inside your staging area, 56 00:02:57,120 --> 00:03:00,090 you can use the Git status command 57 00:03:00,090 --> 00:03:03,060 and it shows you that there are untracked files 58 00:03:03,060 --> 00:03:05,970 which will be shown in red and this is something 59 00:03:05,970 --> 00:03:08,790 that's simply inside your working directory, 60 00:03:08,790 --> 00:03:11,880 but it's not yet in the staging area. 61 00:03:11,880 --> 00:03:14,670 In order to add it to the staging area 62 00:03:14,670 --> 00:03:17,100 and to start tracking changes in it, 63 00:03:17,100 --> 00:03:21,000 then we have to use the command git add. 64 00:03:21,000 --> 00:03:24,480 We're gonna type git add and we're gonna type the file name, 65 00:03:24,480 --> 00:03:27,510 so in this case it's chapter1.txt. 66 00:03:27,510 --> 00:03:29,280 So go ahead and hit Enter. 67 00:03:29,280 --> 00:03:32,280 And then if we try using Git status, again, 68 00:03:32,280 --> 00:03:35,970 you can see that that file has been added as a new file 69 00:03:35,970 --> 00:03:37,350 and it is now green. 70 00:03:37,350 --> 00:03:39,810 So this is now in the staging area 71 00:03:39,810 --> 00:03:41,910 and it's ready to be committed. 72 00:03:41,910 --> 00:03:45,750 So let's go ahead and commit this under version control. 73 00:03:45,750 --> 00:03:49,170 So the command is git commit. 74 00:03:49,170 --> 00:03:54,000 And I'm gonna use the -m flag to add a commit message. 75 00:03:54,000 --> 00:03:56,880 The commit message is really, really important. 76 00:03:56,880 --> 00:04:00,180 It's something that helps you keep track 77 00:04:00,180 --> 00:04:03,420 of what changes you have made in each commit. 78 00:04:03,420 --> 00:04:06,180 So when you create a new save point, 79 00:04:06,180 --> 00:04:09,090 you want to be as explicit as possible 80 00:04:09,090 --> 00:04:12,300 about what changes were made 81 00:04:12,300 --> 00:04:15,390 between the last save point and this current save point. 82 00:04:15,390 --> 00:04:16,800 For our initial commit, 83 00:04:16,800 --> 00:04:20,680 we can use something very simple like Initial commit 84 00:04:21,720 --> 00:04:24,840 and this shows that this is our starting point. 85 00:04:24,840 --> 00:04:28,500 Alternatively, if you wanna be slightly more specific, 86 00:04:28,500 --> 00:04:31,830 because in our case, we've actually completed chapter 1 87 00:04:31,830 --> 00:04:34,713 so you can write Complete Chapter 1. 88 00:04:35,970 --> 00:04:37,500 Now, the thing that you'll realize 89 00:04:37,500 --> 00:04:39,420 is that usually with commit messages, 90 00:04:39,420 --> 00:04:42,000 they are written in the present tense, 91 00:04:42,000 --> 00:04:43,380 and this is the best practice. 92 00:04:43,380 --> 00:04:46,410 So whereas it would probably make more sense, 93 00:04:46,410 --> 00:04:48,360 I guess at least in my head anyways, 94 00:04:48,360 --> 00:04:52,980 to write completed chapter one as this save point. 95 00:04:52,980 --> 00:04:54,660 It's actually by convention 96 00:04:54,660 --> 00:04:57,420 that you should always use the present tense. 97 00:04:57,420 --> 00:05:00,270 So it's like you're submitting your changes now. 98 00:05:00,270 --> 00:05:04,050 Let's go ahead and hit Enter to make our first commit, 99 00:05:04,050 --> 00:05:07,320 and you can see what commits you have made 100 00:05:07,320 --> 00:05:10,650 by using the git log command. 101 00:05:10,650 --> 00:05:12,840 You can see that this commit was made 102 00:05:12,840 --> 00:05:17,840 at this time by this person, and it also has a hash 103 00:05:18,660 --> 00:05:23,660 and this hash uniquely identifies this particular commit. 104 00:05:23,670 --> 00:05:26,790 And then right at the end, you see this commit message 105 00:05:26,790 --> 00:05:29,403 of what this save point was all about. 106 00:05:30,510 --> 00:05:34,980 So now I'm gonna go ahead and create two more chapters. 107 00:05:34,980 --> 00:05:37,423 So let's just create chapter2.txt 108 00:05:41,760 --> 00:05:46,230 and chapter3.txt. 109 00:05:46,230 --> 00:05:48,390 And now we have three chapters 110 00:05:48,390 --> 00:05:52,350 and I'm gonna go in and change some of these text files. 111 00:05:52,350 --> 00:05:54,050 So let's say... 112 00:06:05,670 --> 00:06:08,310 Okay, so that's chapter 2 done. 113 00:06:08,310 --> 00:06:09,960 And finally, let's go ahead 114 00:06:09,960 --> 00:06:13,623 and just open chapter 3 and edit that as well. 115 00:06:25,470 --> 00:06:28,110 All right, so all three files have been changed 116 00:06:28,110 --> 00:06:31,560 and over here in Finder you can actually get a quick peek 117 00:06:31,560 --> 00:06:34,620 at what the contents are, which is gonna be really useful 118 00:06:34,620 --> 00:06:36,000 for me to be able to demonstrate to you 119 00:06:36,000 --> 00:06:39,150 what Git is doing behind the background. 120 00:06:39,150 --> 00:06:43,920 So now let's go ahead and add these two new files 121 00:06:43,920 --> 00:06:45,300 to our staging areas. 122 00:06:45,300 --> 00:06:47,970 So again, if we use Git status, 123 00:06:47,970 --> 00:06:51,570 you can see that there's two files that are untracked 124 00:06:51,570 --> 00:06:53,610 which are only in the working directory 125 00:06:53,610 --> 00:06:56,640 and not yet inside the staging area. 126 00:06:56,640 --> 00:06:59,460 So we can put it into the staging area 127 00:06:59,460 --> 00:07:04,200 by simply adding each of them as we did before, git add, 128 00:07:04,200 --> 00:07:06,990 and writing something like chapter2.txt 129 00:07:06,990 --> 00:07:09,990 and then doing git add chapter3.txt. 130 00:07:09,990 --> 00:07:13,530 But as you can imagine, if you have quite a few files, 131 00:07:13,530 --> 00:07:15,660 then it can get incredibly tedious 132 00:07:15,660 --> 00:07:17,940 having to do this one by one. 133 00:07:17,940 --> 00:07:20,490 So of course there is a better way. 134 00:07:20,490 --> 00:07:22,860 Instead of adding these files one by one, 135 00:07:22,860 --> 00:07:25,230 we can actually simply just say git add 136 00:07:25,230 --> 00:07:29,130 and then use the dot to specify everything 137 00:07:29,130 --> 00:07:31,170 inside this current directory, 138 00:07:31,170 --> 00:07:34,230 so everything inside the Story directory. 139 00:07:34,230 --> 00:07:36,330 Now, if I go ahead and hit Enter 140 00:07:36,330 --> 00:07:38,760 and then let's go to git status again, 141 00:07:38,760 --> 00:07:41,250 you can see that there's two new files 142 00:07:41,250 --> 00:07:44,190 that have been added to the staging area. 143 00:07:44,190 --> 00:07:47,190 And now we're going to commit those two files 144 00:07:47,190 --> 00:07:50,790 to a new commit, to a new save point, 145 00:07:50,790 --> 00:07:52,440 and you know what to do. 146 00:07:52,440 --> 00:07:54,000 If you're following along with me, 147 00:07:54,000 --> 00:07:55,353 go ahead and give it a go. 148 00:07:59,430 --> 00:08:01,530 All right, so how was that? 149 00:08:01,530 --> 00:08:05,490 If you remember, the command is git commit 150 00:08:05,490 --> 00:08:07,320 and we're going to use the m flag 151 00:08:07,320 --> 00:08:09,870 to specify a commit message 152 00:08:09,870 --> 00:08:13,020 and we're going to write a message 153 00:08:13,020 --> 00:08:15,210 that is in the present tense. 154 00:08:15,210 --> 00:08:20,210 So let's say complete chapter 2 and 3. 155 00:08:22,230 --> 00:08:24,600 So that's everything I've done 156 00:08:24,600 --> 00:08:28,890 between the initial commit and this commit. 157 00:08:28,890 --> 00:08:30,450 The only difference is the fact 158 00:08:30,450 --> 00:08:33,539 that I've completed now chapter 2 and chapter 3. 159 00:08:33,539 --> 00:08:36,092 So let's go ahead and hit Enter. 160 00:08:36,929 --> 00:08:39,630 Again, let's check it out using git log. 161 00:08:39,630 --> 00:08:43,260 We can see that we now have two commits 162 00:08:43,260 --> 00:08:45,240 both with different hashes 163 00:08:45,240 --> 00:08:47,790 because they are unique and they are different. 164 00:08:47,790 --> 00:08:50,640 The initial one was Complete Chapter 1 165 00:08:50,640 --> 00:08:53,220 and it was done at this time. 166 00:08:53,220 --> 00:08:56,430 And then later on, about five minutes later, 167 00:08:56,430 --> 00:08:58,440 I completed chapter 2 and 3 168 00:08:58,440 --> 00:09:00,690 and that was the second commit. 169 00:09:00,690 --> 00:09:03,510 And this is where we are at right now. 170 00:09:03,510 --> 00:09:06,480 So you can see by this word HEAD, 171 00:09:06,480 --> 00:09:11,010 this is the position or the current state that we are in. 172 00:09:11,010 --> 00:09:14,520 So I just wanna quickly recap what we've just done. 173 00:09:14,520 --> 00:09:17,490 We created a file in our working directory 174 00:09:17,490 --> 00:09:19,740 inside our Story directory. 175 00:09:19,740 --> 00:09:23,580 So the working directory is the folder or the directory 176 00:09:23,580 --> 00:09:27,240 where you initialize your Git repository. 177 00:09:27,240 --> 00:09:29,130 When we said git init, 178 00:09:29,130 --> 00:09:31,590 we did that inside the Story directory. 179 00:09:31,590 --> 00:09:33,870 So that becomes our working directory. 180 00:09:33,870 --> 00:09:36,120 And from now on, Git is going to try 181 00:09:36,120 --> 00:09:38,430 and track the changes that it sees 182 00:09:38,430 --> 00:09:42,963 between the working directory and the local repository. 183 00:09:43,980 --> 00:09:45,750 In the beginning, we created a file 184 00:09:45,750 --> 00:09:49,050 inside our working directory inside Story 185 00:09:49,050 --> 00:09:54,050 and then we used git add to push it to the staging area. 186 00:09:54,930 --> 00:09:58,440 Now, the reason why there is this intermediate staging area, 187 00:09:58,440 --> 00:10:00,390 'cause you might wonder why not just go 188 00:10:00,390 --> 00:10:03,120 from the working directory straight to the repository? 189 00:10:03,120 --> 00:10:05,430 Why do we need this extra step? 190 00:10:05,430 --> 00:10:07,710 Well, sometimes you might not want 191 00:10:07,710 --> 00:10:11,070 to add all of your files to be tracked 192 00:10:11,070 --> 00:10:13,950 or all of your files to be committed. 193 00:10:13,950 --> 00:10:16,020 So the staging area is a good place 194 00:10:16,020 --> 00:10:17,790 to try and figure out what are the things 195 00:10:17,790 --> 00:10:19,740 that you want git to ignore 196 00:10:19,740 --> 00:10:22,680 and what are the things that you want to be tracked. 197 00:10:22,680 --> 00:10:24,360 Once we've used git add, 198 00:10:24,360 --> 00:10:26,940 we've put our file into the staging area 199 00:10:26,940 --> 00:10:30,660 and we're happy with the changes that we are going to commit 200 00:10:30,660 --> 00:10:34,140 then the next step is to go ahead and commit it 201 00:10:34,140 --> 00:10:36,930 using the git commit command. 202 00:10:36,930 --> 00:10:41,370 So now our file is inside our local repository 203 00:10:41,370 --> 00:10:45,600 and that version is given a name through the commit message. 204 00:10:45,600 --> 00:10:48,930 So that means that even if we've messed up our file, 205 00:10:48,930 --> 00:10:52,680 we can still use the last version 206 00:10:52,680 --> 00:10:54,720 that's under version control 207 00:10:54,720 --> 00:10:56,880 and we can use a special command 208 00:10:56,880 --> 00:11:01,350 called git checkout to revert back or roll back 209 00:11:01,350 --> 00:11:04,920 to the last position in our local repository. 210 00:11:04,920 --> 00:11:07,920 Let me show you what that looks like in the command line 211 00:11:07,920 --> 00:11:10,410 and how we would do that in practice. 212 00:11:10,410 --> 00:11:13,740 At the moment, I've got three nicely written chapters 213 00:11:13,740 --> 00:11:16,290 and I have a feeling in my book it's gonna be a big seller. 214 00:11:16,290 --> 00:11:19,890 Now, let's say that I have, you know, 215 00:11:19,890 --> 00:11:21,540 been working on chapter three 216 00:11:21,540 --> 00:11:24,420 and I have completely messed everything up 217 00:11:24,420 --> 00:11:27,900 and just, you know, fell asleep on my keyboard 218 00:11:27,900 --> 00:11:31,170 and I happen to have saved my file. 219 00:11:31,170 --> 00:11:33,330 And now if you have a look at it, 220 00:11:33,330 --> 00:11:37,680 it's now just mumbo jumbo and I've ruined my masterpiece. 221 00:11:37,680 --> 00:11:40,740 But fear not because we have version control 222 00:11:40,740 --> 00:11:45,740 and we have git enabled, so we have nothing to worry about. 223 00:11:45,870 --> 00:11:48,030 I can actually revert the changes 224 00:11:48,030 --> 00:11:51,300 that I've made locally in my working directory. 225 00:11:51,300 --> 00:11:53,520 So at this point, you can use git status 226 00:11:53,520 --> 00:11:57,870 to see that we have modifications in our chapter3.txt file 227 00:11:57,870 --> 00:12:00,240 that have not yet been committed 228 00:12:00,240 --> 00:12:02,340 or added to the staging area. 229 00:12:02,340 --> 00:12:05,940 So if we wanted to, we can actually revert this 230 00:12:05,940 --> 00:12:08,790 back to its previous glory. 231 00:12:08,790 --> 00:12:12,330 But before we do that, we can use a git command 232 00:12:12,330 --> 00:12:14,610 to check out what are the differences 233 00:12:14,610 --> 00:12:17,040 between the current version of chapter 3 234 00:12:17,040 --> 00:12:20,790 and the last save point in our Git repository. 235 00:12:20,790 --> 00:12:24,270 To do that, you can use the command git diff, 236 00:12:24,270 --> 00:12:25,470 so the difference, 237 00:12:25,470 --> 00:12:29,280 and we'll give it the chapter 3 file name. 238 00:12:29,280 --> 00:12:30,360 And if you hit Enter, 239 00:12:30,360 --> 00:12:33,870 you can see that this is the part that was deleted, 240 00:12:33,870 --> 00:12:35,520 so the part in red, 241 00:12:35,520 --> 00:12:38,790 and then this was the part that was added 242 00:12:38,790 --> 00:12:40,680 which is our gobbledygook. 243 00:12:40,680 --> 00:12:43,110 So now, if I've looked at these differences, 244 00:12:43,110 --> 00:12:46,530 it might just be that, you know, there's only a few mistakes 245 00:12:46,530 --> 00:12:48,660 in my new version of chapter 3 246 00:12:48,660 --> 00:12:51,630 and I just want to maybe copy some things over 247 00:12:51,630 --> 00:12:55,410 or have a look at how I did certain things previously 248 00:12:55,410 --> 00:12:58,080 and change my current file. 249 00:12:58,080 --> 00:13:01,080 But other times it might be that, you know, 250 00:13:01,080 --> 00:13:03,300 it's just you wanna torch the new file. 251 00:13:03,300 --> 00:13:05,520 You just don't want anything to do with it 252 00:13:05,520 --> 00:13:09,330 and you would much rather roll back to the previous version. 253 00:13:09,330 --> 00:13:10,440 So if you want to do that, 254 00:13:10,440 --> 00:13:14,490 then there is a command called git checkout 255 00:13:14,490 --> 00:13:17,160 that is gonna be really, really useful for you. 256 00:13:17,160 --> 00:13:20,730 So git checkout, and then we're gonna specify 257 00:13:20,730 --> 00:13:22,890 the name of the file that we want to check out, 258 00:13:22,890 --> 00:13:25,290 which is chapter3.txt. 259 00:13:25,290 --> 00:13:28,290 And if you just watch over here, which is the preview 260 00:13:28,290 --> 00:13:31,560 of the current version of chapter3.txt, 261 00:13:31,560 --> 00:13:33,900 once I hit Enter on this command, 262 00:13:33,900 --> 00:13:37,620 that basically asks to roll back this chapter 3 263 00:13:37,620 --> 00:13:40,710 to the last version that was committed 264 00:13:40,710 --> 00:13:42,900 in our local repository. 265 00:13:42,900 --> 00:13:46,290 So if I hit Enter, you can see that almost immediately 266 00:13:46,290 --> 00:13:48,600 my chapter 3 has been restored 267 00:13:48,600 --> 00:13:51,720 to its previous glorious state, 268 00:13:51,720 --> 00:13:54,000 and this is the version of chapter 3 269 00:13:54,000 --> 00:13:57,540 at the last checkpoint at which I committed it. 270 00:13:57,540 --> 00:14:01,890 So that was this one, which is completed chapter 2 and 3. 271 00:14:01,890 --> 00:14:04,410 Whereas in this lesson we've looked mostly 272 00:14:04,410 --> 00:14:07,440 at local implementations of Git, 273 00:14:07,440 --> 00:14:11,550 so saving these versions on our computer locally, 274 00:14:11,550 --> 00:14:14,430 in the next lesson I'm gonna talk about GitHub 275 00:14:14,430 --> 00:14:17,190 and creating remote repositories. 276 00:14:17,190 --> 00:14:18,957 So I'll see you there.