1 00:00:00,480 --> 00:00:02,940 In this lesson we're going to discuss git 2 00:00:02,940 --> 00:00:04,650 and its core commands. 3 00:00:04,650 --> 00:00:06,960 Now, most of the time when developers collaborate 4 00:00:06,960 --> 00:00:08,310 for a certain project, 5 00:00:08,310 --> 00:00:11,010 they need to have a distributed version control system, 6 00:00:11,010 --> 00:00:13,020 so they can easily manage the different versions 7 00:00:13,020 --> 00:00:15,680 of the code they're writing and minimize any conflicts, 8 00:00:15,680 --> 00:00:17,520 while being able to revert back 9 00:00:17,520 --> 00:00:19,080 to older versions of the code 10 00:00:19,080 --> 00:00:21,120 if they make any kind of mistake. 11 00:00:21,120 --> 00:00:22,860 In this case, you're going to be able 12 00:00:22,860 --> 00:00:24,960 to use something like Git. 13 00:00:24,960 --> 00:00:27,060 Now let's say you just arrived from your vacation, 14 00:00:27,060 --> 00:00:28,560 and you wanted to check on the progress 15 00:00:28,560 --> 00:00:30,210 that your team has made on a project 16 00:00:30,210 --> 00:00:31,500 that you were working on. 17 00:00:31,500 --> 00:00:33,960 Well, if you had a version control system, 18 00:00:33,960 --> 00:00:35,670 you could very easily do this 19 00:00:35,670 --> 00:00:37,110 by knowing what version it was, 20 00:00:37,110 --> 00:00:40,650 or what date it was last controlled or changed. 21 00:00:40,650 --> 00:00:41,490 Now by far, 22 00:00:41,490 --> 00:00:43,980 the most commonly used modern version control system 23 00:00:43,980 --> 00:00:47,670 in the world is known as Git, G I T. 24 00:00:47,670 --> 00:00:51,600 Now Git is a mature, actively maintained open-source project 25 00:00:51,600 --> 00:00:54,060 that was originally developed back in 2005 26 00:00:54,060 --> 00:00:57,540 by the same person who developed the Linux operating system. 27 00:00:57,540 --> 00:01:00,210 Now a staggering number of software projects rely 28 00:01:00,210 --> 00:01:02,010 on Git for version control, 29 00:01:02,010 --> 00:01:03,960 including a lot of commercial projects, 30 00:01:03,960 --> 00:01:06,540 as well as most of the open source community. 31 00:01:06,540 --> 00:01:08,280 Its core component of Git is known 32 00:01:08,280 --> 00:01:10,170 as the Git repository. 33 00:01:10,170 --> 00:01:12,840 This is a storage area where versions of code 34 00:01:12,840 --> 00:01:15,270 and related files are going to be put. 35 00:01:15,270 --> 00:01:16,740 To get started with Git, 36 00:01:16,740 --> 00:01:18,600 you can use an available package manager 37 00:01:18,600 --> 00:01:20,610 to install the Git package. 38 00:01:20,610 --> 00:01:24,090 To run the git command, simply type in git, the options, 39 00:01:24,090 --> 00:01:25,950 and the subcommand you want. 40 00:01:25,950 --> 00:01:28,140 Now some of the major subcommands that you're going to use 41 00:01:28,140 --> 00:01:31,170 with Git include things like the config subcommand. 42 00:01:31,170 --> 00:01:33,570 This is used to set up options for a repository 43 00:01:33,570 --> 00:01:37,290 or for your Git users, as well as other global options. 44 00:01:37,290 --> 00:01:40,320 The init subcommand is used to create a Git repository 45 00:01:40,320 --> 00:01:42,990 or re-initialize an existing one. 46 00:01:42,990 --> 00:01:45,720 The clone subcommand is used to create a working copy 47 00:01:45,720 --> 00:01:47,520 of an existing repository. 48 00:01:47,520 --> 00:01:50,070 And the add subcommand is used to add files 49 00:01:50,070 --> 00:01:52,410 to be tracked by the Git repository. 50 00:01:52,410 --> 00:01:54,390 The commit subcommand is going to be used 51 00:01:54,390 --> 00:01:56,760 to update the Git repository with your changes, 52 00:01:56,760 --> 00:01:58,710 and this essentially creates a snapshot 53 00:01:58,710 --> 00:02:01,680 of that repository, or a snapshot of the files 54 00:02:01,680 --> 00:02:04,050 at that particular moment in time. 55 00:02:04,050 --> 00:02:06,090 Now the status subcommand is going to be used 56 00:02:06,090 --> 00:02:08,520 to display the status of the repository. 57 00:02:08,520 --> 00:02:11,310 The branch subcommand is used to manage branches 58 00:02:11,310 --> 00:02:14,280 or pointers to specific repository snapshots 59 00:02:14,280 --> 00:02:16,260 after you've committed changes. 60 00:02:16,260 --> 00:02:19,230 The merge subcommand is going to be used to integrate changes 61 00:02:19,230 --> 00:02:21,690 from one branch into a master branch. 62 00:02:21,690 --> 00:02:24,930 The pull subcommand is used to acquire and merge changes 63 00:02:24,930 --> 00:02:27,150 that are made to other repositories and branches 64 00:02:27,150 --> 00:02:29,370 into the local working copy. 65 00:02:29,370 --> 00:02:32,730 The push subcommand is used to upload a local working copy 66 00:02:32,730 --> 00:02:35,370 of a repository to a remote repository, 67 00:02:35,370 --> 00:02:38,310 such as a centralized repository or database. 68 00:02:38,310 --> 00:02:41,220 The log subcommand is used to display the changes made 69 00:02:41,220 --> 00:02:42,840 to a local repository. 70 00:02:42,840 --> 00:02:45,090 And the checkout subcommand is used to switch 71 00:02:45,090 --> 00:02:48,030 to a specific branch that you want to work with. 72 00:02:48,030 --> 00:02:50,700 The tag subcommand is going to be used to add a tag 73 00:02:50,700 --> 00:02:51,960 to your Git repository, 74 00:02:51,960 --> 00:02:53,820 which acts as a specific reference point 75 00:02:53,820 --> 00:02:55,350 in your Git history. 76 00:02:55,350 --> 00:02:57,630 These git tags are used to capture the specific point 77 00:02:57,630 --> 00:02:59,760 in history that is further used to point 78 00:02:59,760 --> 00:03:01,350 to a released version. 79 00:03:01,350 --> 00:03:04,020 Now, this tag doesn't really change a branch, 80 00:03:04,020 --> 00:03:05,880 but instead it just adds a marker 81 00:03:05,880 --> 00:03:07,770 for us to be able to realize what happened 82 00:03:07,770 --> 00:03:09,570 at that given point in time. 83 00:03:09,570 --> 00:03:12,450 The rebase subcommand is one of two Git utilities 84 00:03:12,450 --> 00:03:14,160 that specializes in integrating changes 85 00:03:14,160 --> 00:03:15,840 from one branch into another. 86 00:03:15,840 --> 00:03:17,880 The other one is the merge command. 87 00:03:17,880 --> 00:03:19,530 Now, when we talk about the merge command, 88 00:03:19,530 --> 00:03:22,530 it's always about making a forward-moving change record 89 00:03:22,530 --> 00:03:24,570 that's going to merge both bases into one, 90 00:03:24,570 --> 00:03:25,590 and that's going to become the one 91 00:03:25,590 --> 00:03:27,030 we're going to use moving forward. 92 00:03:27,030 --> 00:03:29,700 But with rebase, we instead are going to use this 93 00:03:29,700 --> 00:03:32,580 to do a rewriting of our historical features. 94 00:03:32,580 --> 00:03:35,250 For example, when we rebase, this is really the process 95 00:03:35,250 --> 00:03:37,470 of moving or combining a sequence of commits 96 00:03:37,470 --> 00:03:39,150 to a new base commit. 97 00:03:39,150 --> 00:03:41,040 Now the primary reason for rebasing is 98 00:03:41,040 --> 00:03:43,260 to maintain a linear project history. 99 00:03:43,260 --> 00:03:44,880 And this allows you to re-baseline 100 00:03:44,880 --> 00:03:47,850 into a new baseline history moving forward. 101 00:03:47,850 --> 00:03:49,380 All right, let's say you need 102 00:03:49,380 --> 00:03:52,230 to create a local repository and commit some changes 103 00:03:52,230 --> 00:03:54,180 to it as you go through the process. 104 00:03:54,180 --> 00:03:56,880 Well, let's talk about the process flow for doing this. 105 00:03:56,880 --> 00:03:59,400 First, you're going to configure global settings, 106 00:03:59,400 --> 00:04:00,690 including the username, 107 00:04:00,690 --> 00:04:05,690 by typing git config dash dash global user.name 108 00:04:06,000 --> 00:04:08,100 quote User quote, 109 00:04:08,100 --> 00:04:10,590 where user's the name of the user you want to create. 110 00:04:10,590 --> 00:04:12,690 Second, you're going to create a directory 111 00:04:12,690 --> 00:04:14,520 where your project's going to reside. 112 00:04:14,520 --> 00:04:16,110 To do this, you're going to type in 113 00:04:16,110 --> 00:04:19,350 mkdir /dev-project, 114 00:04:19,350 --> 00:04:20,970 and then we're going to change ourself 115 00:04:20,970 --> 00:04:23,670 into that directory by using the CD command. 116 00:04:23,670 --> 00:04:26,730 Now, we want to initialize this directory using Git 117 00:04:26,730 --> 00:04:28,530 to make it a Git repository. 118 00:04:28,530 --> 00:04:29,760 So we'll do this by typing 119 00:04:29,760 --> 00:04:33,720 git init /dev-project. 120 00:04:33,720 --> 00:04:34,950 Now, at this point, 121 00:04:34,950 --> 00:04:38,100 we want to put some project files into this repository. 122 00:04:38,100 --> 00:04:39,180 These are going to be the files 123 00:04:39,180 --> 00:04:41,160 that make up the actual development project 124 00:04:41,160 --> 00:04:43,740 that we're storing and controlling, using Git. 125 00:04:43,740 --> 00:04:45,960 In Git, you create a working copy 126 00:04:45,960 --> 00:04:47,700 by using the clone subcommand. 127 00:04:47,700 --> 00:04:52,700 So, we're going to type in git clone /dev-project. 128 00:04:53,280 --> 00:04:57,090 Next we're going to type git add myfile. 129 00:04:57,090 --> 00:04:59,040 And this will add the project files 130 00:04:59,040 --> 00:05:02,970 into the Git tracking system, specifically, myfile. 131 00:05:02,970 --> 00:05:05,220 Next, we want to be able to commit the changes 132 00:05:05,220 --> 00:05:07,410 by taking a snapshot of our project. 133 00:05:07,410 --> 00:05:09,630 So at this stage, we're going to enter a message 134 00:05:09,630 --> 00:05:11,910 that summarizes what changes we made. 135 00:05:11,910 --> 00:05:16,277 For example, I might type in git commit -m, 136 00:05:16,277 --> 00:05:20,460 and then quote, initial commit or whatever message I want, 137 00:05:20,460 --> 00:05:21,660 end quote. 138 00:05:21,660 --> 00:05:23,970 Now at this point, if we want to see the status 139 00:05:23,970 --> 00:05:27,420 of our Git repository, we can type in git status, 140 00:05:27,420 --> 00:05:29,010 and this will retrieve the current status 141 00:05:29,010 --> 00:05:30,600 of the changed files. 142 00:05:30,600 --> 00:05:33,240 So if I had three files that were being worked on 143 00:05:33,240 --> 00:05:34,980 for a particular step in this project, 144 00:05:34,980 --> 00:05:37,320 but only two were ready to be committed at this time, 145 00:05:37,320 --> 00:05:40,920 those would show up here as added, but not yet committed. 146 00:05:40,920 --> 00:05:44,070 Another option here is to work with Git branches. 147 00:05:44,070 --> 00:05:45,330 Now branching is a feature 148 00:05:45,330 --> 00:05:48,000 in most modern version control systems. 149 00:05:48,000 --> 00:05:49,710 In Git, branches are part 150 00:05:49,710 --> 00:05:51,840 of your everyday development process, 151 00:05:51,840 --> 00:05:53,940 and Git branches are effectively a pointer 152 00:05:53,940 --> 00:05:56,970 to a snapshot of your different changes you've made. 153 00:05:56,970 --> 00:05:59,580 When you want to add a new feature or a fix or a bug, 154 00:05:59,580 --> 00:06:01,140 no matter how big or small, 155 00:06:01,140 --> 00:06:04,680 you're going to spawn a new branch to encapsulate your changes. 156 00:06:04,680 --> 00:06:07,290 By creating a branch in the master copy of the code, 157 00:06:07,290 --> 00:06:08,797 you're going to be able to then work on that 158 00:06:08,797 --> 00:06:11,640 without affecting all the other developers. 159 00:06:11,640 --> 00:06:14,430 To do this, you're going to type git branch, 160 00:06:14,430 --> 00:06:16,627 and then the name of the new branch that you want. 161 00:06:16,627 --> 00:06:18,630 Then whenever you're done, and you need 162 00:06:18,630 --> 00:06:21,360 to merge those changes back into the master branch, 163 00:06:21,360 --> 00:06:23,250 you're going to type git merge, 164 00:06:23,250 --> 00:06:25,020 and the name of that new branch. 165 00:06:25,020 --> 00:06:27,420 This will be able to make those changes and put them back 166 00:06:27,420 --> 00:06:29,810 into the master branch, and doing so allows you 167 00:06:29,810 --> 00:06:31,616 to create new and improved versions 168 00:06:31,616 --> 00:06:34,263 of the software and the master branch. 169 00:06:35,130 --> 00:06:37,830 Now, this is one of the reasons that Git is so powerful, 170 00:06:37,830 --> 00:06:40,440 is this ability to create branches and then put them back 171 00:06:40,440 --> 00:06:43,170 and commit them into the main master branch. 172 00:06:43,170 --> 00:06:45,510 This allows Git to be very collaborative, 173 00:06:45,510 --> 00:06:48,570 and it really becomes game-changing for software developers. 174 00:06:48,570 --> 00:06:50,610 So, so far we've been collaborating 175 00:06:50,610 --> 00:06:52,830 with our most important collaborator, right? 176 00:06:52,830 --> 00:06:54,780 We've been working with ourself, 177 00:06:54,780 --> 00:06:56,700 but Git allows us to collaborate 178 00:06:56,700 --> 00:07:00,000 with somebody else or with lots of other people, as well, 179 00:07:00,000 --> 00:07:02,190 as long as they're also going to have the same privileges 180 00:07:02,190 --> 00:07:04,020 to our Git repository. 181 00:07:04,020 --> 00:07:06,930 Normally, there's going to be some sort of a process flow 182 00:07:06,930 --> 00:07:09,357 when you're collaborating with other developers using Git, 183 00:07:09,357 --> 00:07:10,710 and you're going to work that out, 184 00:07:10,710 --> 00:07:13,080 based on your organizational requirements. 185 00:07:13,080 --> 00:07:15,181 For example, a standard way of doing this 186 00:07:15,181 --> 00:07:17,910 might be to first type git pull, 187 00:07:17,910 --> 00:07:19,710 and then pull in the other branch 188 00:07:19,710 --> 00:07:22,170 to pull the other developers' code and changes, 189 00:07:22,170 --> 00:07:24,510 and merge them into your local repository. 190 00:07:24,510 --> 00:07:28,470 Then you might type git push and the remote repository 191 00:07:28,470 --> 00:07:31,050 with your branch to push your own changes back 192 00:07:31,050 --> 00:07:32,730 to that remote repository. 193 00:07:32,730 --> 00:07:34,920 This allows developers all over the world 194 00:07:34,920 --> 00:07:36,450 to pull and push changes 195 00:07:36,450 --> 00:07:39,750 into the central repository so they can all work together. 196 00:07:39,750 --> 00:07:42,420 Now, any changes made locally are then going to be uploaded 197 00:07:42,420 --> 00:07:45,630 to that central repository using that push command. 198 00:07:45,630 --> 00:07:47,340 And you can see what changes were merged 199 00:07:47,340 --> 00:07:50,400 and what other actions were taken on that repository. 200 00:07:50,400 --> 00:07:51,720 Again, if you want to be able 201 00:07:51,720 --> 00:07:53,820 to see what's inside your project directory, 202 00:07:53,820 --> 00:07:56,400 you can type git log, and that's going to be able 203 00:07:56,400 --> 00:07:58,544 to tell you all the changes that have happened 204 00:07:58,544 --> 00:08:00,630 over a certain period of time. 205 00:08:00,630 --> 00:08:01,470 For example, 206 00:08:01,470 --> 00:08:05,880 if I enter git log dash dash since equals 10 dot days, 207 00:08:05,880 --> 00:08:07,770 I'm going to see all the commits that have happened 208 00:08:07,770 --> 00:08:09,600 in the last 10 days. 209 00:08:09,600 --> 00:08:12,330 I can use this information to troubleshoot any issues 210 00:08:12,330 --> 00:08:13,290 that may have come up 211 00:08:13,290 --> 00:08:16,170 in the last 10 days, or anything I might have missed 212 00:08:16,170 --> 00:08:18,750 if I was on vacation for the last 10 days. 213 00:08:18,750 --> 00:08:21,210 Another thing you can do is you can navigate and switch 214 00:08:21,210 --> 00:08:24,330 between branches of a project by using the checkout command 215 00:08:24,330 --> 00:08:25,620 inside of Git. 216 00:08:25,620 --> 00:08:28,140 To do this you'll type git checkout 217 00:08:28,140 --> 00:08:30,480 and the specific branch you want to check out. 218 00:08:30,480 --> 00:08:32,909 This enables developers to focus their attention 219 00:08:32,909 --> 00:08:35,309 on different branches of the same project, 220 00:08:35,309 --> 00:08:37,799 and really hone in on what they're working on. 221 00:08:37,799 --> 00:08:39,299 Now, another thing that we need to talk about 222 00:08:39,299 --> 00:08:42,390 is this file known as the git ignore file. 223 00:08:42,390 --> 00:08:45,060 This is written as dot gitignore, 224 00:08:45,060 --> 00:08:47,550 and it's a file that exists within the repository. 225 00:08:47,550 --> 00:08:50,100 The purpose of this file is to identify files 226 00:08:50,100 --> 00:08:52,666 that should be ignored during a commit action. 227 00:08:52,666 --> 00:08:56,190 For example, you might have a read me dot TXT file, 228 00:08:56,190 --> 00:08:58,560 or a project to do dot TXT list 229 00:08:58,560 --> 00:08:59,970 that's inside this directory, 230 00:08:59,970 --> 00:09:01,320 and you don't need that to be committed 231 00:09:01,320 --> 00:09:03,712 as part of the project, but it does reside 232 00:09:03,712 --> 00:09:07,020 inside your project directory just for your convenience. 233 00:09:07,020 --> 00:09:09,690 Well, if you're going to use those and you list them out 234 00:09:09,690 --> 00:09:12,480 inside the git ignore file, those will get ignored 235 00:09:12,480 --> 00:09:14,190 when you do a commit. 236 00:09:14,190 --> 00:09:17,970 Another thing that's important is the star dot git slash. 237 00:09:17,970 --> 00:09:20,370 This is a directory that contains all the files 238 00:09:20,370 --> 00:09:23,070 that Git is going to use to manage version control 239 00:09:23,070 --> 00:09:24,630 for your project. 240 00:09:24,630 --> 00:09:26,910 It's going to be a single location where Git stores 241 00:09:26,910 --> 00:09:28,380 all of its information. 242 00:09:28,380 --> 00:09:30,900 Think about it like almost like a flat database. 243 00:09:30,900 --> 00:09:33,630 The directory here resides in the project directory, 244 00:09:33,630 --> 00:09:35,520 and it's created with the git init command 245 00:09:35,520 --> 00:09:37,470 at the beginning of your project. 246 00:09:37,470 --> 00:09:40,920 So as you can see, there is a lot to know inside of Git, 247 00:09:40,920 --> 00:09:44,010 but the good news is, for Linux Plus, you're not going to need 248 00:09:44,010 --> 00:09:45,540 to know it fully in depth. 249 00:09:45,540 --> 00:09:48,360 Git is something used heavily by software developers, 250 00:09:48,360 --> 00:09:51,090 and not nearly as much by system administrators. 251 00:09:51,090 --> 00:09:52,500 It's something you should know about, 252 00:09:52,500 --> 00:09:53,700 but you're not going to have to be an expert 253 00:09:53,700 --> 00:09:54,903 on it for the exam.