Meld is a free, open-source, and cross-platform (UNIX/Linux, OSX, Windows) diff/merge tool.

Here's how to install it on:

• Ubuntu
• Mac
• Windows: "The recommended version of Meld for Windows is the most recent release, available as an MSI from https://meldmerge.org"

This is an vi editor window. This is happening because git cannot perform a fast forward and is prompting you for a message for a merge commit. Vi has a bit of a learning curve and can be confusing for new users.

First, I'd like to mention that you can change what this editor is via the core.editor gitconfig setting. I've included the docs for that below, which describe how to change the editor to emacs (another text editor):

core.editor
By default, Git uses whatever you’ve set as your default text editor via one of the shell environment variables VISUAL or EDITOR, or else falls back to the vi editor to create and edit your commit and tag messages. To change that default to something else, you can use the core.editor setting:

git config --global core.editor emacs

You can find a list of editor configs here. For other editors, you might have to do some tinkering or googling.

Secondly, I'd like to provide the basics on how to use vi and how commit messages are formatted. Regarding commit messages, the first line is the subject line. An optional body can be added to provide greater detail. It is below the subject line and is separated from it via a blank line.

Vi consists of several, but primarily three modes, NORMAL, INSERT and VISUAL. When first opening vi, you're in NORMAL mode, which is primarily used for navigation. You can begin typing once you enter INSERT mode, and you can select text to be cut or copied in VISUAL mode. Here are some key keybindings:

• i enters INSERT mode at the current position
• Esc lets you return to NORMAL mode from INSERT/VISUAL mode
• h lets you move left in NORMAL mode
• j lets you move down in NORMAL mode
• k lets you move up in NORMAL mode
• l lets you move right in NORMAL mode
• u lets you undo changes while in NORMAL mode
• C-r / Ctrl r lets you redo changes while in NORMAL mode
• :wq while in NORMAL mode will write and quit the editor. Doing this allows you to continue with the merge, once you're satisfied with the message.
• :cq while in NORMAL mode will quit vim and throw a compiler error. I find this useful if I want to inspect an interactive rebase without actually doing it. NOTE: if you do this while merging you'll end up in the MERGING git state. You'd have to use git merge --continue to continue the merge or git merge --abort to abort the merge.

EDIT: The format of a commit message is:

Subject line 

body text 

Here's a commit message example as well:

    Merge branch 'jc/revert-show-parent-info'

    * jc/revert-show-parent-info:
      revert: config documentation fixes

In this example, the line beginning with Merge branch is the subject line and the line beginning with the asterisk is the start of the body.

For the window you posted, the subject would be: Merge remote-tracking branch 'origin/Diego2' and it will not contain a body. This is perfectly fine unless you want to add more detail about what's introduced by the merge. If you're satisfied with the current message, press Esc to ensure you're in NORMAL mode followed by :wq to save and quit vi.

beyondcompare ftw

Use the --no-edit option, you can read about it in the documentation.

Note that using the default message is discuraged, since it provides no meaningful information about the changes introduced with this merge.

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On a sidenote: To continue merging you probably have to close the editor.

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If you have a git version prior to 1.7.8 there is still a way to achieve what you want by using the env command.

env GIT_EDITOR=: git merge <ref-you-want-to-merge>

For easier usage you could create an alias.

git config --global alias.merge-no-edit '!env GIT_EDITOR=: git merge'

Which then can be used using git merge-no-edit <ref-you-want-to-merge>.

I've always used KDiff3 . It looks pretty basic, but is very powerful particularly if you learn its keyboard shortcuts. It has three panes at the top: the common ancestor and then the two conflicting versions. Below you have the final version that you create by selecting changes from one of the three versions above.

Free and open source: Meld is freely available on Linux, Windows and OSX (through MacPorts, Fink or Brew). · It's also open source and distributed under the GNU General Public License (GPL). | Confusing UI: Can't tell which file is which if they have the same filename. | No option to compare individual rows horizontally: Unlike other options, like Beyond Compare, Meld has no option to compare individual rows horizontally. | Auto-merge is incomplete: Waste of time (for git), auto-merge leaves out one of the sides, no matter how you configure it. It is not possible to work just on the conflicting changes. | Can't compare differently-named files when comparing directories | Supports editing files directly: In addition to comparing two files it also allows you to edit them right in place. What's more, the diffs are updated automatically. | Fast on Linux: Relatively fast on Linux. | Three way comparisons: You can compare up to three different files for differences. Plus you can edit files from the comparison view and the diff will automatically update. | Simple GUI: SImple, clear overview. | Windows Installer is broken | Easy to use and visually appealing: Straightforward and you don't need to read tutorials to use it. Just click and select and you instantly see how the difference and merges are connected to each other. · 3 sub- windows, instead of 4, which reduces the mess during merge and let you see more of the surrounding files rather than just 5 lines. | On Windows it opens a bunch of cmd windows which sometimes fail to close: It looks like it's using batch scripts for some processes. | Bad merge logic: UI is fine but merge logic is bizarre at best. | No official OSX Support: Some attempts have been made to port, but nothing easy or fully working. | Comparing two or more different folders is supported: Meld allows users to compare two or three different folders for differences. But if a user wants to 'zoom in' and compare files contained in these folders, Meld gives you the ability to do so and launch file comparisons between files contained in different folders or in the same folder. | Slow on large files: While larger files are supported, they can take a long time to load. (20,000 lines+) · See also here. | Supports some simple version control actions: Meld supports the major version control systems (Git, Mercurial, Subversion and Bazaar). You can launch file comparisons between different versions to see what parts changed before commiting. · Simple version control actions are also supported and possible. For example: commit/update/add/remove/delete files. | Internationalization: Through the GNOME Translation project and the translators that have worked for it, Meld is available in multiple languages. You can check if your language is supported in the translation statistics page. · If you can't find your language or if your language translation is unfinished and you want to help, you can do so by joining the GNOME Translation Project. | I have been using Meld as a merge tool and Kdiff3 as a diff tool. I feel both are a little bit complicated to understand at the beginning. | Waste of time (for git), auto-merge leaves out one of the sides, no matter how you configure it. It is not possible to work just on the conflicting changes. | No way to take both changes on merge