Git/C2/The-git-checkout-command/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on git checkout command.
00:06	In this tutorial, we will learn how to: * add multiple files to Git repository
00:12	* Remove a file from Git repository
00:16	* Restore the removed file
00:18	* Discard the changes made to a file and
00:21	* Revert to an earlier revision.
00:25	For this tutorial, I am using: Ubuntu Linux 14.04,
00:31	Git 2.3.2 and gedit Text Editor.
00:36	You can use any editor of your choice.
00:40	To follow this tutorial, you must have knowledge of running Linux commands on Terminal.
00:47	If not, for relevant Linux tutorials, please visit our website.
00:52	Now, let us see how to add multiple files to the Git repository.
00:58	Press Ctrl+Alt+T to open the terminal.
01:02	We will go into our Git repository "mywebpage" which we created earlier.
01:09	Type: cd space mywebpage and press Enter.
01:14	I will continue to use html files for demonstration.
01:19	You may use any file type of your choice.
01:23	We will create 2 html files now.
01:27	So, type: gedit space mystory.html space mynovel.html space ampersand.
01:37	We use the & (ampersand) to free up the prompt. Press' Enter.
01:43	I will copy and paste some code into these files, from my Writer document, which I had saved earlier.
01:50	Let us save these fies.
01:53	In the terminal, first check the Git status by typing git space status and press Enter.
02:03	It shows two untracked files.
02:06	We will now add the untracked files for tracking.
02:10	Type: git space add space dot and press Enter.
02:17	The git add dot command will add all the untracked files to the staging area.
02:23	Hence, the two files "mystory.html" and "mynovel.html" are added to the staging area.
02:32	Let’s check the Git status once again by typing git space status and press Enter.
02:40	Now, we can see that both our files have been added to the staging area of the Git repository.
02:47	Let us switch back to our files mystory.html and mynovel.html.
02:54	Now, we will add a few more lines of code to both these files.
03:00	Like before, I will copy-paste from my Writer document.
03:05	Once again save and close the files.
03:08	Let’s check the Git status by typing git space status and press Enter.
03:16	It shows “Changes not staged for commit” and “modified: mynovel.html" and "mystory.html”.
03:26	This means that the changes we made, have not been added to the staging area.
03:32	Let us now commit our work at this point.
03:36	So, type: git space commit space hyphen a space hyphen m space within double quotes “Added two files” and press Enter.
03:50	Note that we didn't add the modified files to the staging area before committing them and
03:57	the editor also didn't open up for committing message as we saw in earlier tutorial.
04:03	This is because, here we have used hyphena and hyphen m flags.
04:10	So, what are these flags for?
04:13	Switch back to our slides.
04:15	Hyphen 'a' flag is used to add all the modified files to the staging area.
04:21	When we use hyphen a flag, we don’t need git add command separately to add the modified files to the staging area.
04:30	Hyphen m flag is used to give commit message in the command line itself.
04:36	We can use the flags hyphen a and hyphen m as hyphen am.
04:42	Switch back to the terminal.
04:45	Check the Git log by typing git space log and press Enter.
04:52	You can see the list of commits.
04:54	Note that the latest commits are listed first
04:58	which means the commits are listed in chronological order.
05:03	In case, you have added a wrong file to the Git repository, it can be easily removed.
05:10	Say, for example, I want to remove the file mypage.html.
05:16	Type: git space rm space hyphen hyphen cached space mypage dot html and press Enter.
05:26	This command will remove the file mypage.html from the staging area.
05:32	We will check the Git status now by typing git space status and press Enter.
05:40	It says that the file mypage.html is untracked.
05:45	Now, we can delete the file from file system by typing
05:49	rm space mypage dot html and press Enter.
05:55	This command would completely remove the file from mywebpage folder.
06:00	Now, we will check whether the file has been removed from the Git repository.
06:06	So, type: git space status and press Enter.
06:12	It shows the message “deleted: mypage.html”.
06:16	Now, list the files by typing "ls" and press Enter.
06:21	Here, we cannot see the file mypage.html anymore as it has been deleted.
06:28	At this point, let’s freeze our code.
06:32	To commit, type: git space commit space hyphen am space within double quotes “Deleted mypage.html” and press Enter.
06:45	Let’s see the Git log by typing git space log and press Enter.
06:51	Press q key on your keyboard to exit.
06:55	Here, we can find the latest commit by reading the commit message.
06:59	Now, suppose that we have deleted mypage.html by mistake and now we want to restore it back.
07:08	What can we do?
07:09	We can restore the deleted file from the previous commits.
07:13	Let’s restore our file from the second commit, which has the commit message “Added two files”.
07:20	Select the first five digits of the second commit hash
07:24	and press Ctrl + Shift + C keys to copy them.
07:28	The first five digits are sufficient.
07:31	But you can copy more than five digits also, if you wish to.
07:36	Type: git space checkout space and press Ctrl + Shift + V keys to paste the commit hash.
07:45	Now, type the file name "mypage.html" and press Enter.
07:51	Check the Git status by typing git space status and press Enter.
07:58	Now, you can see the file mypage.html.
08:02	Let us commit our work at this point.
08:05	Note that it is very important to commit our work whenever we add or delete any file.
08:12	Type: git space commit space hyphen am space “Restored mypage.html” and press Enter.
08:22	Now, list the files by typing ls and press Enter.
08:28	We can see that our file mypage.html is restored.
08:33	Next, we will see how to discard the changes made to a file.
08:38	Open the files by typing gedit space mypage.html space mystory.html space ampersand and press Enter.
08:50	We will do some modifications in mypage.html and mystory.html.
08:58	Let us add and delete some lines in both the files.
09:03	Then save and close the files.
09:06	In certain situations, we may not want to continue with these changes.
09:11	That means, we want to go back to the previous stage of our work.
09:16	Let us learn how to do it.
09:19	First, we will check the Git status by typing git space status and press Enter.
09:27	It says that some files have been modified.
09:30	Now, type: git space checkout space dot and press Enter.
09:37	This command will delete the latest changes of our work.
09:41	Check the Git status by typing git space status and press Enter.
09:48	It says “nothing to commit”.
09:51	Let us check the files to see whether the changes are still there or not.
09:57	Type: gedit space mypage.html space mystory.html & and press Enter.
10:07	We can see that our modifications have been discarded. Close the files.
10:13	Now, let us check the Git log by typing git space log and press Enter.
10:20	It shows list of commits.
10:23	Press down arrow key to see more.
10:26	Press q key on your keyboard to exit.
10:30	If you want to see the commits list in one line, type: git space log space hyphen hyphen oneline and press Enter.
10:42	Here, you can see the commits list with their commit hash and commit messages in one line.
10:48	How can we go to a previous revision of our work?
10:53	Currently we have four commits in our repository
10:56	which means, we have four revisions of our work.
11:01	Say, we want to go back to the “Initial commit” stage.
11:05	So, type: git space checkout space, then copy and paste the commit hash of the Initial commit and press Enter.
11:15	List the files by typing ls and press Enter.
11:19	We can see only one file mypage.html here, because in this stage, we had only this file.
11:28	Now, check the Git log by typing git space log and press Enter.
11:34	We can see the first commit only i.e. the Initial commit.
11:39	To return back to the current revision, type: git space checkout space master and press Enter.
11:48	We will learn more about the term master in future tutorials.
11:53	Let’s check the Git log once again by typing
11:57	git space log space hyphen hyphen oneline and press Enter.
12:03	Now you can see all four commits. So, we are now at the latest stage.
12:10	In this manner, we can go back to any stage of our work.
12:14	There is another way to go to the old revision.
12:18	Type: git space reset space hyphen hyphen hard.
12:23	Then copy and paste the commit hash of the Initial commit and press Enter.
12:29	Check the Git log by typing git space log and press Enter.
12:35	It shows that we are now at the Initial commit stage.
12:39	Now, let’s try to go back to the latest revision.
12:43	Like before, type: git space checkout space master and press Enter.
12:51	We are unable to go back to the latest revision.
12:55	Instead, we get a message: “Already on 'master'”.
12:58	It means this is our latest revision.
13:02	So, note, once we use the command git reset hyphen hyphen hard, we can't go back to the latest stage.
13:11	So, we should be very careful with this command.
13:15	With this, we come to the end of this tutorial.
13:18	Let us summarize. In this tutorial, we have learnt how to: *Add multiple files to Git repository
13:27	* Remove a file from Git repository. * Restore the removed file
13:32	* Discard the changes made to a file and * Revert to an earlier revision.
13:39	As an assignment- Go to your Git repository which you created in the previous tutorial assignment.
13:46	Do some modifications in your text file.
13:49	Commit the changes.
13:52	Try to revert to your old revision.
13:55	Again do some modifications in your text file and try to discard the changes.
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14:34	This is Priya from IIT Bombay. Thanks for joining.

Contributors and Content Editors

PoojaMoolya, Sandhya.np14