`master` is a reference to the end of a branch. By convention (and by default) this is usually the main integration branch, but it doesn&#39;t have to be.

`HEAD` is actually a special type of reference that points to another reference. It may point to `master` **or it may not** (it will point to whichever branch is currently checked out). If you know you want to be committing to the `master` branch then push to this.

Here is a visual example:

![alt text][1]

On your own repository you can check where the `HEAD` is pointing to by running this:

    $ git symbolic-ref HEAD
    refs/heads/master

However, finding out where the `remotes/origin/HEAD` is pointing to is more tricky because it is on the remote machine.

&lt;s&gt;There is a great little tutorial on git references here:

http://people.gnome.org/~federico/news-2008-11.html#pushing-and-pulling-with-git-1&lt;/s&gt;


  [1]: http://i.stack.imgur.com/hRanK.png

The simple answer is that `HEAD` is a pointer/label to the most recent commit of the branch you are currently on. `master` is the default branch created when you initialized a git repository (e.g. `git init`).

You can delete the `master` branch (e.g. `git branch -D master`). You cannot delete the `HEAD` pointer.

Simply push the changes of your current branch

    git push origin

and it will push your branch &#39;`B`&#39; changes to &#39;`origin/B`&#39;.  
If you are on your `master` branch, git will push to `origin/master`.  
Actually it will push all changes on the local branches that have matching remote branches at `origin`. It is controlled by the config setting **[push.default][1]**.  
See also [pushing RefSpecs in the Pro Git book][2].

----

What you are seeing is the sidebar representing all the refspecs of your remote repo in the [Experimental GitX fork][3] of the [GitX project][4].

![alt text][5]

The `HEAD` will designate the default branch for that remote.  
See [`git remote set-head` man page][6]:

&gt; Having a default branch for a remote is not required, but allows the name of the remote to be specified in lieu of a specific branch.  
For example, if the default branch for `origin` is set to `master`, then `origin` may be specified wherever you would normally specify `origin/master`. 


  [1]: https://stackoverflow.com/questions/948354/git-push-current-branch/948397#948397
  [2]: http://progit.org/book/ch9-5.html#pushing_refspecs
  [3]: http://brotherbard.com/blog/2010/03/experimental-gitx-fork/
  [4]: http://gitx.frim.nl/
  [5]: http://i.stack.imgur.com/pfckK.jpg
  [6]: http://www.kernel.org/pub/software/scm/git/docs/git-remote.html

I have 2 questions:

Q1. Where exactly does &quot;business logic&quot; lie in the MVC pattern? I am confused between Model and Controller.

Q2. Is &quot;business logic&quot; the same as &quot;business rules&quot;? If not, what is the difference?

It would be great if you could explain with a small example.

Business logic in MVC

I was wondering if there is a way to do this purely in sql:

    q1 = SELECT campaign_id, from_number, received_msg, date_received 
         FROM `received_txts` WHERE `campaign_id` = &#39;8&#39;;
    INSERT INTO action_2_members (campaign_id, mobile, vote, vote_date)    
        VALUES(q1.campaign_id, q1.from_number, q1.received_msg, q1.date_received);

&lt;strong&gt;Note: &lt;/strong&gt;q1 would return about 30k rows.

Is there any way to do what I am attempting above in straight sql?
To just pull the data straight from one table (basically a raw data table) and insert into another table (basically a processed data table)?


mySQL :: insert into table, data from another table?

What is the difference between the `HEAD` and `master` in Git?

I did a clone of a project on GitHub and want to push my changes to the remote. But to which one should I push?

![screenshot](https://i.stack.imgur.com/2yC3l.png)

Difference between HEAD and master

What is the difference between the <code>HEAD</code> and <code>master</code> in Git?
I did a clone of a project on GitHub and want to push my changes to the remote. But to which one should I push?
<img src="https://i.stack.imgur.com/2yC3l.png" alt="screenshot">

Something wrong is going on with one of the files in my local git repository. When I&#39;m trying to change the branch it says:

    Unlink of file &#39;templates/media/container.html&#39; failed. Should I try again? (y/n)

What could that mean?

Unlink of file Failed. Should I try again?

I&#39;ve renamed a couple of files using `git mv`, used `git stash`, had a quick look at HEAD (without changing it) then did `git stash pop` to get the whole lot back again. My moves had disappeared from the commit list, so I redid them with `git rm` and the commit message claimed git had spotted the rename was a rename. So I thought no more of it.

But now, post-commit, I can&#39;t get at the history of the moved files! Here&#39;s what git says about the commit in question:

    ~/projects% git log --summary
    commit de6e9fa2179ae17ec35a5c368d246f19da27f93a
    Author: brone
    Date:   Wed Dec 8 22:37:54 2010 +0000
    
        Moved R_DebugUI into runtime
    
     delete mode 100644 test/R_DebugUI_iOS.h
     delete mode 100644 test/R_DebugUI_iOS.m
     create mode 100644 system/runtime/src/R_DebugUI_iOS.h
     create mode 100644 system/runtime/src/R_DebugUI_iOS.m

     &lt;&lt;snip older commits&gt;&gt;
     ~/projects%

I&#39;m now trying to get the history of one of these moved files, so I can look at an old version, but I don&#39;t get anything very useful:

    ~/projects/system/runtime/src% git log --follow --find-copies-harder -M -C R_DebugUI_iOS.m
    commit de6e9fa2179ae17ec35a5c368d246f19da27f93a
    Author: brone
    Date:   Wed Dec 8 22:37:54 2010 +0000
    
        Moved R_DebugUI into runtime
    ~/projects/system/runtime/src% 

(I&#39;ve also tried it without `-M`, `-C` and `--find-copies-harder`, but to no avail.)

I can get its history under its old name, which stops at the point it was deleted from its old location:

    ~/projects% git log --summary --follow --find-copies-harder -M -C -- test/R_DebugUI_iOS.m
    commit de6e9fa2179ae17ec35a5c368d246f19da27f93a
    Author: brone
    Date:   Wed Dec 8 22:37:54 2010 +0000
    
        Moved R_DebugUI into runtime
    
     delete mode 100644 test/R_DebugUI_iOS.m
    
    commit 32a22d53c27e260714f759ecb3d3864e38b2e87f
    Author: brone
    Date:   Tue Dec 7 23:52:51 2010 +0000
    
        Can set debug UI&#39;s alpha.
    
    &lt;&lt;snip older commits&gt;&gt;
    ~/projects%

So I&#39;m not completely stuck this time, but I wouldn&#39;t fancy having to do this kind of thing all the time. (I anticipate having a fair number of files that will move at least once in their life.)

Am I doing something wrong? The old copy of the file and the new copy are 98.8% the same (2 lines out of 166 changed). My understanding is that git should be able to track the file in this case, because it infers rename operations rather than storing them explicitly, and the files are similar enough that I believe it should consider them the same.

Is there anything I can do to fix this?


Why might git log not show history for a moved file, and what can I do about it?

We are new to git, and I want to set a tag at the beginning of our repository. 
Our production code is the same as the beginning repository, but we&#39;ve made commits since then.
A tag at the beginning would allow us to &quot;roll back&quot; production to a known, stable state.

So how to add a tag to an arbitrary, older commit?

How to tag an older commit in Git?

`git blame` is great for modified and added lines, but how can I find when a line that existed in a specific previous commit was eventually deleted.  I&#39;m thinking `bisect`, but I was hoping for something handier.

(Before you ask: in this case, I just did a `git log -p` and searched through for the code line and (a) some idiot had *just* deleted the vital line in the previous commit and (b) I was that idiot.)


How do I &quot;git blame&quot; a deleted line?

I have a fork (`origin`) from a project (`upstream`) on github. Now the upstream project has added a new branch, I want to import into my fork. How do I do that?

I tried checking out the remote and creating a branch on top of that, but that configures the branch the way that `git push` is trying to push to the `upstream`:

    git checkout upstream/branch
    git checkout -b branch

### edit

Maybe that wasn&#39;t clear, but I want to add the branch to my local repository, so I can push it to `origin` (my fork) via `git push`. Because upstream repositories are usually read-only and you fork it to contribute.

So I basically want to checkout a non-existent branch on `origin` whose contents will be pulled in from `upstream`.

Github: Import upstream branch into fork

I&#39;m not sure, but I have a vague memory of creating a github pull request with &quot;Issue 4&quot; or something in the title, and it automatically attached itself to Issue 4 in the project that I was submitting it to. I tried it again recently and it didn&#39;t work -- it just created a brand new issue instead. I don&#39;t see any options like &quot;Attach to issue&quot; on the new pull request page, nor &quot;Open a new pull request for this issue&quot; on the issue page. Is there any way to do this, to help project owners keep their Issues page clean and avoid duplication?

**Edit**: To clarify, I know that creating a pull request always creates a *new* issue. I would like to instead attach the pull request to an *existing* issue.

How do you attach a new pull request to an existing issue on github?

JetBrains IntelliJ IDEA has 2 plugins: **Git** and **Github**. Do I need to install Git from http://git-scm.com on my local windows machine in order to upload my files to GitHub through IntelliJ IDEA?

Do I need Git to use Github in JetBrains IntelliJ IDEA?

What are some tips on downloading a single file from a GitHub repo?

I don&#39;t want the URL for displaying the raw file; in the case of binaries, there&#39;s nothing.

http://support.github.com/discussions/feature-requests/41-download-single-file

Is it even possible to use GitHub as a &quot;download server&quot;?

If we decide to switch to Google Code, is the mentioned functionality presented there?

Or is there any free-of-charge hosting and VCS for open-source projects?


  [1]: https://en.wikipedia.org/wiki/Revision_control


Download single files from GitHub

How can I import source code from my computer to my GitHub account?


Import existing source code to GitHub

I know that Git tracks changes I make to my application, and it holds on to them until I commit the changes, but here&#39;s where I&#39;m hung up:

When I want to revert to a previous commit I use: 

&lt;pre&gt;&lt;code&gt;git reset --hard HEAD&lt;/code&gt;&lt;/pre&gt;

And Git returns:

    HEAD is now at 820f417 micro

How do I then revert the files on my hard drive back to that previous commit?

My next steps were:

    git add .
    git commit -m &quot;revert&quot;

But none of the files have changed on my hard drive...

What am I doing right/wrong?


How do I use &#39;git reset --hard HEAD&#39; to revert to a previous commit?

Is there a pythonic way to unpack a list in the first element and the &quot;tail&quot; in a single command?

For example:

    &gt;&gt; head, tail = **some_magic applied to** [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
    &gt;&gt; head
    1
    &gt;&gt;&gt; tail
    [1, 2, 3, 5, 8, 13, 21, 34, 55]

Head and tail in one line

I am setting-up a REST web service that just need to answer YES or NO, as fast as possible.

Designing a HEAD service seems the best way to do it but I would like to know if I will really gain some time versus doing a GET request. 

I suppose I gain the body stream not to be open/closed on my server (about 1 millisecond?).
Since the amount of bytes to return is very low, do I gain any time in transport, in IP packet number? 

Thanks in advance for your response!


**Edit:**

To explain further the context: 

 - I have a set of REST services executing some processes, if they are in an active state.
 - I have another REST service indicating the state of all these first services.

Since that last service will be called very often by a very large set of clients (one call expected every 5ms), I was wondering if using a HEAD method can be a valuable optimization? About 250 chars are returned in the response body. HEAD method at least gain the transport of these 250 chars, but what is that impact?

I tried to benchmark the difference between the two methods (HEAD vs GET), running 1000 times the calls, but see no gain at all (&lt; 1ms)...


http HEAD vs GET performance

Is there any way to access the first element of a Series without knowing its index?

Let&#39;s say I have the following Series:

    import pandas as pd

    key=&#39;MCS096&#39;
    SUBJECTS = pd.DataFrame(
        {
            &quot;ID&quot;: pd.Series([146], index=[145]),
            &quot;study&quot;: pd.Series([&quot;MCS&quot;], index=[145]),
            &quot;center&quot;: pd.Series([&quot;Mag&quot;], index=[145]),
            &quot;initials&quot;: pd.Series([&quot;MCS096&quot;], index=[145]),
        }
    )


Print out `SUBJECTS`:

    print(SUBJECTS[SUBJECTS.initials==key][&#39;ID&#39;])
    &gt;&gt;&gt; 145    146
    &gt;&gt;&gt; Name: ID, dtype: int64

How can I get the value 146 here without using index 145?

Get first element of Series without knowing the index

This seems like a ridiculously easy question... but I&#39;m not seeing the easy answer I was expecting.

So, how do I get the value at an nth row of a given column in Pandas? (I am particularly interested in the first row, but would be interested in a more general practice as well).

For example, let&#39;s say I want to pull the 1.2 value in `Btime` as a variable.

Whats the right way to do this?

```python
&gt;&gt;&gt; df_test
    ATime   X   Y   Z   Btime  C   D   E
0    1.2  2  15   2    1.2  12  25  12
1    1.4  3  12   1    1.3  13  22  11
2    1.5  1  10   6    1.4  11  20  16
3    1.6  2   9  10    1.7  12  29  12
4    1.9  1   1   9    1.9  11  21  19
5    2.0  0   0   0    2.0   8  10  11
6    2.4  0   0   0    2.4  10  12  15
```

Get first row value of a given column

I set up a branch in the remote repository and made some commits on that branch.
Now I want to merge the remote branch to the remote master.

Basically follows are my operations:

1. checkout branch
2. checkout master
3. merge branch and fix merging errors
4. commit
5. push origin HEAD:refs/for/master

But get error messages on the 5th step:

    remote: Resolving deltas:   0% (0/12)
    
    remote: ERROR: missing Change-Id in commit message
    ...
    
    remote: Change-Id: I55862204ef71f69bc88c79fe2259f7cb8365699a
    
    To ssh://prc@test.gerrit.xxx.com:29418/hello_git
     ! [remote rejected] HEAD -&gt; refs/for/master (missing Change-Id in commit message)


Gerrit error when Change-Id in commit messages are missing

I have an ES cluster with 4 nodes:

    number_of_replicas: 1
    search01 - master: false, data: false
    search02 - master: true, data: true
    search03 - master: false, data: true
    search04 - master: false, data: true

I had to restart search03, and when it came back, it rejoined the cluster no problem, but left 7 unassigned shards laying about.  

    {
      &quot;cluster_name&quot; : &quot;tweedle&quot;,
      &quot;status&quot; : &quot;yellow&quot;,
      &quot;timed_out&quot; : false,
      &quot;number_of_nodes&quot; : 4,
      &quot;number_of_data_nodes&quot; : 3,
      &quot;active_primary_shards&quot; : 15,
      &quot;active_shards&quot; : 23,
      &quot;relocating_shards&quot; : 0,
      &quot;initializing_shards&quot; : 0,
      &quot;unassigned_shards&quot; : 7
    }

Now my cluster is in yellow state.  What is the best way to resolve this issue?

- Delete (cancel) the shards?
- Move the shards to another node?
- Allocate the shards to the node?
- Update &#39;number_of_replicas&#39; to 2?
- Something else entirely?

Interestingly, when a new index was added, that node started working on it and played nice with the rest of the cluster, it just left the unassigned shards laying about.

Follow on question: am I doing something wrong to cause this to happen in the first place?  I don&#39;t have much confidence in a cluster that behaves this way when a node is restarted.  

**NOTE:** If you&#39;re running a single node cluster for some reason, you might simply need to do the following:

    curl -XPUT &#39;localhost:9200/_settings&#39; -d &#39;
    {
        &quot;index&quot; : {
            &quot;number_of_replicas&quot; : 0
        }
    }&#39;

Content Type	Original Author	Original Content on Stackoverflow
Question	Frederik Heyninck	View Question on Stackoverflow
Solution 1 - Git	Lee Netherton	View Answer on Stackoverflow
Solution 2 - Git	benhorgen	View Answer on Stackoverflow
Solution 3 - Git	VonC	View Answer on Stackoverflow

Difference between HEAD and master

Git Problem Overview

Git Solutions

Solution 1 - Git

Solution 2 - Git

Solution 3 - Git

mySQL :: insert into table, data from another table?

Business logic in MVC

Attributions