.. _hg:
=============================================================
Mercurial (hg)
=============================================================
See :ref:`versioncontrol` and the links there
for a more general discussion of the concepts.
.. _classhg:
Instructions for cloning the class repository
---------------------------------------------
All of the materials for this class, including slides, sample programs,
and the webpages you are now
reading (or at least the *.rst* files used to create them, see
:ref:`sphinx`), are in a Mercurial repository hosted at Bitbucket, located
at
``_.
In addition to viewing the files via the link above, you can also view
changesets, issues, etc. (see :ref:`bitbucket`).
To obtain a copy, simply move to the directory where you want your copy to
reside (assumed to be your home directory below)
and then *clone* the repository::
$ cd
$ hg clone http://bitbucket.org/rjleveque/uwamath583s11/
Note the following:
* It is assumed you have Mercurial (hg) installed, see
:ref:`software_installation`.
* The clone statement will download the entire repository as a new
subdirectory called *uwamath583s11*, residing in your home directory. If you
want *uwamath583s11* to reside elsewhere, you should first *cd* to that
directory.
It will be useful to set a Unix environment variable (see :ref:`env`) called
*CLASSHG* to refer to the directory you have just created. Assuming you are
using the bash shell (see :ref:`bash`), and that you cloned uwamath583s11
into your home directory, you can do this via::
$ export CLASSHG=$HOME/uwamath583s11
This uses the standard environment variable *HOME*, which is the full path
to your home directory.
If you put it somewhere else, you can instead do::
$ cd uwamath583s11
$ export CLASSHG=`pwd`
The syntax
*`pwd`* means to run the *pwd* command (print working directory) and insert the
output of this command into the export command.
Type::
$ printenv CLASSHG
to make sure *CLASSHG* is set properly. This should print the full path to the
new directory.
If you log out and log in again later, you will find that this environment
variable is no longer set. Or if you set it in one terminal window, it
will not be set in others. To have it set automatically every time a new
bash shell is created (e.g. whenever a new terminal window is opened), add a
line of the form::
export CLASSHG=$HOME/uwamath583s11
to your *.bashrc* file. (See :ref:`bashrc`). This assumes it is in your
home directory. If not, you will have to add a line of the form::
export CLASSHG=full-path-to-uwamath583s11
where the full path is what was returned by the *printenv* statement above.
.. _classhg_update:
Updating your clone
-------------------
The files in the class repository will change as the quarter progresses ---
new notes, slides, sample programs, and homeworks will be added. In order
to bring these changes over to your cloned copy, all you need to do is::
$ cd $CLASSHG
$ hg pull
$ hg update
Of course this assumes that *CLASSHG* has been properly set, see above.
The last two command can be combined as::
$ hg pull -u
.. _myhg:
Creating your own Bitbucket repository
--------------------------------------
In addition to using the class repository, students in AMath 483/583 are
also required to create their own repository on Bitbucket. It is possible
to use Mercurial for your own work without creating a repository on a hosted
site such as Bitbucket (see :ref:`newhg` below), but there are several
reasons for this requirement:
* You should learn how to use Bitbucket for more than just pulling changes.
* You will use this repository to "submit" your solutions to homeworks.
You will give the instructor and TA permission to clone your repository so
that we can grade the homework (others will not be able to clone or view it
unless you also give them permission).
* It is recommended that after the class ends you
continue to use your repository as a way to back up your important work on
another computer (with all the benefits of version control too!).
At that point, of course, you can change the permissions so the
instructor and TA no longer have access.
Below are the instructions for creating your own repository. Note that
this should be a *private repository* so nobody can view or clone it unless
you grant permission.
Anyone can create one free private repository on Bitbucket. More than one
costs money. If you already have a private repository that you don't want
to give us access to, contact us and we can arrange something else.
(Note that you can also create an unlimited number of public repositories
free at Bitbucket, which you might want to do for open source software
projects, or for classes like this one.)
Follow these directions exactly. Doing so is part of :ref:`homework1`.
We will clone your repository and check that *testfile.txt* has been created
and modified as directed below.
.. comment:: Homework 1 is subject to change and these instructions may be
modified, so you might want to wait until the quarter starts.
#. On the machine you're working on, go to your home directory ("cd $HOME"
on Unix) and create a file named .hgrc
(with a dot at the front) containing::
[ui]
username = Your Name
verbose = True
This will be used when you commit changes. This is a configuration file
used by hg, similar to the :ref:`bashrc` used by bash.
If you don't do this, you might get a message like::
abort: no username supplied (see "hg help config")
the first time you try to commit.
#. Go to ``_ and click on "Sign up now"
#. Fill in the form, make sure you remember your username and password.
#. You should then be taken to your account. Click on "+ Create new" next
to "Your repositories".
#. You should now see a form where you can specify the name of a repository
and a description. The repository name need not be the same as your user
name (a single user might have several repositories). For example, the class
repository is named *uwamath583s11*, owned by user *rjleveque*.
To avoid confusion, you should probably not name your repository
*uwamath583s11*.
#. Make sure you click on "Private" at the bottom. Also keep "Issue
tracking" and "Wiki" clicked on.
#. Click on "Create repository".
#. You should now see a page with instructions on how to *clone* your
(currently empty) repository. In a Unix window, *cd* to the directory where
you want your cloned copy to reside, and perform the clone by typing in
the clone command shown. This will create a new directory with the same
name as the repository.
#. You should now be able to *cd* into the directory this created.
#. To keep track of where this directory is and get to it easily in the
future, create an environment variable *MYHG* from inside this directory
by::
$ export MYHG=`pwd`
See the discussion above in section :ref:`classhg` for what this does. You
will also probably want to add a line to your *.bashrc* file to define MYHG
similar to the line added for *CLASSHG*.
#. The directory you are now in will appear empty if you simply do::
$ ls
But try::
$ ls -a
./ ../ .hg/
the *-a* option causes *ls* to list files starting with a dot, which are
normally suppressed. See :ref:`ls` for a discussion of *./* and *../*.
The directory *.hg* is the directory that stores all the information
about the contents of this directory and a complete history of every file
and every change ever committed. You shouldn't touch or modify the files in
this directory, they are used by Mercurial.
#. Add a new file to your directory::
$ cat > testfile.txt
This is a new file
with only two lines so far.
^D
The Unix *cat* command simply redirects everything you type on the
following lines into a file called *testfile.txt*. This goes on until
you type a -d (the 4th line in the example
above). After typing -d you should get the Unix
prompt back. Alternatively, you could create the file testfile.txt using
your favorite text editor (see :ref:`editors`).
#. Type::
$ hg status
The response should be::
? testfile.txt
The ? means that this file is not under revision control. To put it
under revision control, type::
$ hg add testfile.txt
$ hg status
A testfile.txt
The A means it has been added. However, at this point Mercurial is not
yet keeping track of this version or any changes to this file. We can
tell Mercurial to track this version by::
$ hg commit testfile.txt -m "My first commit of a test file."
The string following the -m is a comment about this commit that may help
you in general remember why you committed new or changed files.
If you left off the file name *testfile.txt* then be default hg will
commit all changes made in this directory since the last commit. In the
current example there is only one change, the addition of this file, so
it would have the same behavior either way.
We can now see the status of our directory via::
$ hg status --all
C testfile.txt
Now the C means this file is *clean* (agrees with the version being
tracked). If you leave off the *--all* flag, by default *hg status*
does not list the clean files and only shows files that differ from the
lastest version being tracked. This is generally what you want if you
have thousands of files in your repository and only a few have been changed.
Alternatively, you can check the status of a single file with::
$ hg status testfile.txt
Now let's modify this file::
$ cat >> testfile.txt
Adding a third line
^D
Here the *>>* tells *cat* that we want to add on to the end of an
existing file rather than creating a new one. (Or you can edit the file
with your favorite editor and add this third line.)
Now try the following::
$ hg status
M testfile.txt
The M indicates this file has been modified relative to the most recent
version that was committed.
To see what changes have been made, try::
$ hg diff testfile.txt
This will produce something like::
diff -r 6e3383561936 testfile.txt
--- a/testfile.txt Tue Mar 02 23:15:38 2010 -0800
+++ b/testfile.txt Tue Mar 02 23:23:57 2010 -0800
@@ -1,2 +1,3 @@ This is a new file
This is a new file
with only two lines so far
+Adding a third line
The + in front of the last line shows that it was added.
The two lines before it are printed to show the context. If the
file were longer, *hg diff*
would only print a few lines around any change to indicate the context.
The first line printed out above shows the diff command that's actually
being executed: it is doing a diff between this file and the one stored
in the revision that Mercurial has given the name 6e3383561936.
Internally it creates long hexidecimal names like this (see :ref:`hex`)
in order to keep things straight if changes made by several different
people are merged. There's a simpler revision number you can discover
by typing::
$ hg tip
changeset: 0:6e3383561936
tag: tip
user: rjl@spinach
date: Tue Mar 02 23:15:38 2010 -0800
summary: My first commit of a test file.
This shows that the *tip* (the most recent version of all files being
tracked) is changeset 0.
Now let's commit this changed file::
$ hg commit -m "added a third line to the test file"
After this, "hg tip" should indicate the changeset of the tip is 1
(along with a long hex string).
#. So far you have been using Mercurial to keep track of changes in your own
directory, on your computer. None of these changes have been seen by
Bitbucket, so if someone else cloned your repository from there, they
would not see *testfile.txt*.
Now let's *push* these changes back to the Bitbucket repository::
First do::
$ hg status
to make sure there are no changes that have not been committed. This
should print nothing.
Now do::
$ hg push
This will prompt for your Bitbucket password and should then print
something like::
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
Not only has it copied the 1 file over, it has added both changesets, so
the entire history of your commits is now stored in the repository. If
someone else clones the repository, they get the entire commit history
and could revert to any previous version, for example (see
:ref:`hg_revert`).
#. Check that the file is in your Bitbucket repository: Go back to that web
page for your repository and click on the "Source" tab at the top. It
should display the files in your repository and show *testfile.txt*.
Now click on the "Changesets" tab at the top. It should show that you
made two commits and display the comments you added with the *-m* flag
with each commit.
Look on the right side, where it says "commit 1: hex-string". The
hex-string is the internal identifier of this commit. If you click on
the hex-string it will show the *change set* for this commit. What you
should see is the file in its final state, with three lines. The third
line should be highlighted in green, indicating that this line was added
in this changeset. A line highlighted in red would indicate a line deleted
in this changeset. (See also :ref:`bitbucket`.)
This is enough for now!
:ref:`homework1` instructs you to add some additional files to the Bitbucket
repository.
Feel free to experiment further with your repository at this point.
See :ref:`hg_more` for some more examples of how hg can be used.
Further reading
---------------
Next see :ref:`bitbucket`.
Remember that you can get help with Mercurial commands by typing, e.g.::
$ hg help
$ hg diff help
See [Bitbucket-hg-intro]_ for an overview or [hgbook]_ for complete
details, [hg-faq]_ for an FAQ, and [hg-hgrc]_ for more about
configuration files.
The site `` has many other
useful things to read. In particular, to help get started, see:
* `QuickStart
`_
* `Tutorial
`_
* `ChangeSetComments
`_
* `UnderstandingMercurial
`_
* `RepositoryNaming
`_