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+
+---------------------------------
+Version Control using Hg  Part 3
+---------------------------------
+
+.. Prerequisites
+.. -------------
+
+.. Version Control with hg - Part 1,2
+
+.. Author : Primal Pappachan
+   Internal Reviewer :
+   Date: Jan 27, 2012
+   
+   
+--------
+Script
+--------
+
+.. L1
+
+{{{ Show the first slide containing title, name of the production team along with the logo of MHRD}}}
+
+.. R1
+
+Hello friends and welcome to the tutorial on 'Version Control with Hg' 
+
+.. L2
+
+{{{Show the slide 'Prerequisite'}}}
+
+.. R2
+
+Please make sure that you have gone through the following tutorials before you
+continue on this tutorial
+
+.. L3
+
+{{{Show the slide containing the objectives}}}
+
+.. R3
+
+At the end of this tutorial you will be able to
+ 1. Learn how to view and revert changes made to files in a repository.
+ #. Learn how to share repositories and deal with simultaneous conflicting changes.
+
+.. L4
+
+{{{Show the slide 'Operational overhead?'}}} 
+
+.. R4 
+
+Let's first try to find out why we should commit inspite of the additional operational costs and loss of time?
+
+.. L4
+
+{{{Show the slide 'Revert Changes'}}}
+
+.. R4
+
+While you were wondering, let's say your friend walks in and together you make
+a lot of changes. You replace all the occurrences of & in chapter1.txt with and. 2. You delete
+the chapter3.txt file.
+
+.. L5 
+
+$ rm chapter3.txt
+$ hg st
+M chapter1.txt
+! chapter3.txt
+
+.. R6
+
+But after a while, you realize that these changes are unwarranted. You want to
+go back to the previous state, undoing all the changes that you made, after
+your friend arrived.
+
+The undo in your editor may allow undoing some changes(if you haven't closed it after making the changes) but there's no way of getting back deleted files using your editor. That's where mercurial comes to the rescue.
+
+We shall use the revert command of hg to undo all the changes after the last commit. If we want to undo all the changes, we use the revert command with the --all argument, else use revert command with specific filename as argument.
+
+.. L5
+
+$ hg revert --all
+reverting chapter1.txt
+reverting chapter3.txt
+$ hg st
+? chapter1.txt.orig
+$ ls
+chapter1.txt  chapter1.txt.orig  chapter2.txt  chapter3.txt
+
+.. R5
+
+After running this command, you can see that all deleted files have been restored.
+But hg has generated new files with .orig extension.  Mercurial actually doesn't like 
+to delete any of the changes that you have made. So, it makes a back-up of the already 
+existing files in the present state and gives you back the old file.
+
+If we now decide, that we want to redo the changes that we had done to the
+existing file, we can just overwrite it with the backed up file. 
+
+.. L6
+
+$ mv chapter1.txt.orig chapter1.txt
+$ hg st
+M chapter1.txt
+
+.. L7
+
+{{{Show the slide 'Viewing Changes'}}}
+
+.. R6
+
+Let's say we now want to commit these changes, but we are not sure of all the changes that we have made to the file, since it's been a while after we made the changes. We could use the diff command to see all the changes that have been made in the file.
+
+.. L8
+
+$ hg diff
+
+.. R7
+
+You see some cryptic output, but it's essentially giving you the list of changes made to the file. All the lines that were deleted are preceded by a - and all the new-lines are preceded by a +. You can see that the & occurrences have been replaces with and. 
+
+We should note here that, the diff wouldn't make much sense, if we had some
+binary files like .jpg or .pdf files. We would see some gibberish in the
+output. Let's now commit this change.
+
+.. L9
+
+$hg commit
+$hg log
+
+.. R8
+
+We can pass an additional argument, -v or --verbose, to hg log to get the whole
+commit message, instead of just the summary.
+
+.. L10
+
+$hg log -v
+
+.. R9
+
+Also, we are not always, interested to see the whole history of the project. It
+would often suffice to see the last few commits.
+
+.. L11
+
+$ hg log -v -l3
+
+.. R10
+
+To limit the output of hg log, we could use the -l or --limit argument. Now it
+will print only last three commits.
+
+.. L12
+
+{{{Show the slide 'Revision Numbering'}}}
+
+.. R11
+
+Often, the level of detail provided by the commit messages is also not enough.
+We would want to see what exactly changed with a commit, probably as a diff. We
+could do that using revision numbers. 
+
+Use the log command to get a brief description of all the changes made, by
+showing us the summary line of all the commits. Look at the changeset line in
+the output of the command. It shows a number followed by a semi-colon and some
+long hexa-decimal string. The number is called the revision number. It is an
+identifier for the commit, and can be along with various commands to specify
+the revision number, if required. 
+
+.. L13
+
+{{{Show the slide  'Using revision numbers'}}}
+
+
+.. R12
+
+The revision number can also be passed as an argument to many commands. Let's say we wish to see the changes between revision 1 and revision 2. We shall use the diff command to do this.
+
+.. L14
+
+$ hg diff -r1 -r2
+
+.. R13
+
+The diff command takes two revision numbers as arguments and gives the changes made from revision in the first argument to revision in the second argument.
+
+.. R14
+
+It can be passed to other commands as well. For instance, we can check the logs of the very first commit, by saying
+
+.. L15
+
+$ hg log -r0
+
+.. R15
+
+You could also specify a range of commits whose logs you would like to see. Say, we would like to see the last two commits,
+
+.. L16
+
+$ hg log -r0:2
+
+.. R16 
+
+To see changes made to a particular file, in the speciifed range of commits, 
+
+.. L17
+
+$ hg log -r0:2 chapter2.txt
+
+
+.. R17
+
+This brings us to the end of the tutorial. In this tutorial, we have
+seen,
+
+.. L18
+
+{{{Show the 'summary' slide'}}}
+
+.. R18
+
+In this tutorial, we have learnt to, 
+ 1. Undo changes to the repository using hg revert,
+ #. View changes done to the repository using hg diff
+ #. Use revision numbers as arguments to different hg commands
+
+.. L19
+
+{{{ Show self assessment questions slide }}}
+
+.. R19
+
+Here are some self assessment questions for you to solve
+
+
+.. L20
+
+{{{ Solution of self assessment questions on slide }}}
+
+.. R20
+
+And the answers,
+
+
+
+.. L21
+
+{{{ Show the Thank you slide }}}
+
+.. R21
+
+Hope you have enjoyed this tutorial and found it useful.
+Thank you!
+
+
+
+
+
+
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+