1 00:00:00,063 --> 00:00:04,088 In the last two movies we've taken a look at a soft reset and a mixed reset. 2 00:00:04,088 --> 00:00:09,003 In this movie we're going to take a look at the hard reset, or a Git reset 3 00:00:09,003 --> 00:00:10,098 using the hard option. 4 00:00:10,098 --> 00:00:15,026 Now, of the three this is the most destructive, because all three of them rewind 5 00:00:15,026 --> 00:00:21,026 the HEAD pointer to point to another commit, but the other two leave the files 6 00:00:21,026 --> 00:00:25,042 either in our staging index or in our working directory so that we then have 7 00:00:25,042 --> 00:00:29,050 those changes still at hand ready to remake those commits. 8 00:00:29,050 --> 00:00:30,099 The hard reset doesn't do that. 9 00:00:30,099 --> 00:00:36,092 Hard reset makes our staging index and our working directory exactly match the repo. 10 00:00:36,092 --> 00:00:39,065 It throws out everything that happened after that. 11 00:00:39,065 --> 00:00:43,018 Those commits are not just sitting there waiting for us to recommit, we're now 12 00:00:43,018 --> 00:00:47,023 essentially rewound back to that previous commit. 13 00:00:47,023 --> 00:00:50,016 That makes it the easiest way for you to lose data. 14 00:00:50,016 --> 00:00:55,010 The main time that you want to use a git reset hard is when things have really 15 00:00:55,010 --> 00:00:58,035 just gotten out of hand in your working directory, they're just completely out 16 00:00:58,035 --> 00:01:00,085 of sync, that's what git reset hard is great at. 17 00:01:00,085 --> 00:01:04,035 It just says, you know what, I don't want everything that happened after that. 18 00:01:04,035 --> 00:01:08,079 I really wish I could go back and just do a hard reset to this point and then 19 00:01:08,079 --> 00:01:11,078 move forward from there. So let's try it. 20 00:01:11,078 --> 00:01:15,098 Again, just like on the other two, grab some of these commits and put those into 21 00:01:15,098 --> 00:01:20,059 a new text file, so then we'll have these references to these later commits if 22 00:01:20,059 --> 00:01:22,021 we decide that we want to go back to them. 23 00:01:22,021 --> 00:01:26,078 And the commit that we're going to roll back to is going to be the same one, 24 00:01:26,078 --> 00:01:28,078 we'll just go back to that right there. 25 00:01:28,078 --> 00:01:34,004 So it's git reset with the hard option to this SHA right here so that's going to 26 00:01:34,004 --> 00:01:38,015 rewind back and undo the revert commit that we made. 27 00:01:38,015 --> 00:01:44,013 So it tells us HEAD is now at this point, and it gives us the name of that. 28 00:01:44,013 --> 00:01:48,051 If we take a look at the log, we'll see that in fact that's what it points to, 29 00:01:48,051 --> 00:01:50,003 that's the most recent commit. 30 00:01:50,003 --> 00:01:54,033 And if we do git status, you'll see that it tells us our working directory is 31 00:01:54,033 --> 00:01:57,027 clean, there's no trace of that file. 32 00:01:57,027 --> 00:02:02,011 There is no trace of the changes that we made to resources.html. 33 00:02:02,011 --> 00:02:06,013 Now, we can at this point do our revert again if we wanted to, if we wanted to 34 00:02:06,013 --> 00:02:10,013 do it over, or if we just thought we wanted to do something different, we've now 35 00:02:10,013 --> 00:02:14,042 essentially rewound our project back to this previous point in time. 36 00:02:14,042 --> 00:02:18,047 I said that it throws everything away, that's not entirely true, it doesn't 37 00:02:18,047 --> 00:02:21,056 throw everything away, it's just not sitting here waiting for us to make those 38 00:02:21,056 --> 00:02:23,049 commits, it's not at hand. 39 00:02:23,049 --> 00:02:28,095 However, those old commits are still there, we can still move our HEAD back to 40 00:02:28,095 --> 00:02:30,069 this later point in time. 41 00:02:30,069 --> 00:02:38,021 So let's do that, git reset --hard, and we'll put in the later commit again, it 42 00:02:38,021 --> 00:02:42,093 now moved it up there, that git object was still there, it's still sitting there 43 00:02:42,093 --> 00:02:47,058 in the git folders, it had just moved the HEAD pointer away from it. 44 00:02:47,058 --> 00:02:50,065 At some point if we hadn't done anything with it, it would have gotten garbage 45 00:02:50,065 --> 00:02:54,008 collected and thrown away, that would have been a long ways down the line. 46 00:02:54,008 --> 00:02:59,083 It would have hung on to it for a while just to make sure that we didn't want to go back to it. 47 00:02:59,083 --> 00:03:04,058 But it wouldn't have been easy to go back to it if we didn't record this reference right here. 48 00:03:04,058 --> 00:03:07,083 We wouldn't have those changes in our working directory, and we wouldn't know 49 00:03:07,083 --> 00:03:11,058 the name of the commit that would take us back there to get to it. 50 00:03:11,058 --> 00:03:15,058 So unlike the other two examples that we did with reset, let's go ahead and take 51 00:03:15,058 --> 00:03:17,083 the additional step of making a new commit here. 52 00:03:17,083 --> 00:03:21,033 So let's do git log, and instead of just reverting this commit, let's rewind 53 00:03:21,033 --> 00:03:24,096 back here before we even rearrange the items the first time. 54 00:03:24,096 --> 00:03:30,093 So I'm going to use this 2907 as the SHA, let's do git reset --hard, and let's 55 00:03:30,093 --> 00:03:36,099 rewind back to that point. So now it's rewound us back to git log. 56 00:03:36,099 --> 00:03:43,018 You can see we're back to removed contractions from page text, git status, you 57 00:03:43,018 --> 00:03:46,045 can see that there's nothing in my staging index or working directory. 58 00:03:46,045 --> 00:03:51,034 And if we open up resources.html, and we scroll down to that list, you'll see 59 00:03:51,034 --> 00:03:54,080 that it's back in its original state. 60 00:03:54,080 --> 00:03:58,005 So it essentially did the reversion by allowing us to rewind. 61 00:03:58,005 --> 00:04:01,073 Let's say that we now want to make additional changes though and go forward. 62 00:04:01,073 --> 00:04:07,005 Let's say that we want to just move sunglasses up here after hat, put it right 63 00:04:07,005 --> 00:04:13,016 in front of hat, and then I'll save it, close it, git status. Let's do git 64 00:04:13,016 --> 00:04:17,092 commit, and we're going to use the -a option, which is going to commit all of my 65 00:04:17,092 --> 00:04:24,050 changes all at once with the message, and we're going to say "Moved sunglasses 66 00:04:24,050 --> 00:04:30,030 higher in list of suggested outdoor items". 67 00:04:30,030 --> 00:04:36,072 So now it's made my new commit. Nothing in my directory. Git log. 68 00:04:36,072 --> 00:04:38,098 Now I've put a new commit here. 69 00:04:38,098 --> 00:04:44,086 So now, after this one comes this one, I've essentially rewound in time and started recording. 70 00:04:44,086 --> 00:04:50,014 And now my HEAD pointer points to this new commit, and all my future commit will just come off of that. 71 00:04:50,014 --> 00:04:53,056 Those other commits that we made, they're now just lost, they're sitting there 72 00:04:53,056 --> 00:04:57,089 abandoned in the git folder and they will eventually get garbage collected. 73 00:04:57,089 --> 00:05:02,058 So that's how you use the three different forms of reset, soft, mix, and hard. 74 00:05:02,058 --> 00:05:08,013 Again, just be careful when you use them, because they do allow you to overwrite data.