understanding commits in git?

Question

First of all I'm new to web development in general and so let me know if I make any obvious mistakes.

So I decided that if I want to start making websites I'm probably going to need to learn Git and GitHub.

I currently understand how to initialize a repository, stage and commit and push it all to a GitHub page. What I'm struggling with now is the process of reverting back to an old commit. So lets say I've made two commits called commit 1, commit 2 respectively.

If I'm on commit 2 how to I go back to commit 1?? Can I go back to commit one change code commit the changes and still go back to commit 2 after?? What specifically happens to the code and files when moving between commits.

Please feel free to talk to me like a 5 year old who understands nothing to do with Git and the command line. Thanks in advance guys.

It sounds like you should spend some quality time with a basic git tutorial (of which there are many from which to choose). — larsks
– larsks, Commented Aug 10, 2015 at 14:58
@larsks yeah I've been reading alot of tutorials but the seem written for programmers to understand. They never explain the logic of whats happening in certain situations and this confuses me lots. Any tutorials you would recommend — mikey
– mikey, Commented Aug 10, 2015 at 15:04

neshkeev · Accepted Answer · 2015-08-11 07:08:24Z

You can use the reset command to navigate over the history. See how easy it is, at first let's create two files:

$ touch a
$ touch b

Let's commit one of them:

$ git add a
$ git co -m "First commit"
[master d263314] First commit
 1 file changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 a

Let's commit the other one:

$ git add b
$ git co -m "Second commit"
[master 16aa86a] Second commit
 1 file changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 b

Now let's check the history out:

$ git log --oneline
16aa86a Second commit
d263314 First commit
38df137 Initial commit

As you can see there are three commits and they have hash codes to distingush them. There is a special pointer that points at the commit that is on top of the history. It is called HEAD. When the a file was committed HEAD pointed at this commit, but when the second file was committed HEAD started to point at the second commit.

The reflog command helps you to track history where HEAD pointed.

$ git reflog
16aa86a HEAD@{0}: commit: Second commit
d263314 HEAD@{1}: commit: First commit
38df137 HEAD@{2}: commit (initial): Initial commit

In order to get rid of the most recent commit, you need to make HEAD point at one of the previous commits. This is when the reset command appears.

$ git reset --hard HEAD@{1}
HEAD is now at d263314 First commit

Be carefull, all your unstaged data gets lost. Let's check the history out:

$ git log --oneline
d263314 First commit
38df137 Initial commit

But it is possible to jump not only to one of previous commits, it is possible to jump at any commit as well, let's get back to the second commit:

$ git reset --hard 16aa86a
HEAD is now at 16aa86a Second commit

Let's check the history out:

$ git log --oneline
16aa86a Second commit
d263314 First commit
38df137 Initial commit

As you can see the history gets restored

Get some time and read this amazing book I guarantee you will become a highly expirienced Git user

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