Git Difftool For Code Reviews

On 8 minutes, 24 seconds read By Edward
A picture of meld differences to signify Git Difftool visual diff

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Mastering Git Difftool

The git diff is a command used to compare changes between 2 versions of a file or between 2 commits in a Git Repository. Git also allows a user to set their preferred diff tool using the git difftoolcommand.

Web designers and application developers can use Git to track changes or versions. Git is a distributed version control system (dvcs). Every repository (local copy of source code) contains the complete history therefore rendering a central server redundant or network independent.

The focus of this tutorial will be using the Git Difftool.

  1. Setting up a local repository and initializing your project.
  2. Making changes, staging files, and committing with meaningful messages.
  3. Pushing your changes to a remote repository.

Requirements For Using Git

Glossary:

Distributed Version Control System

(DVCS) tracks versions of files.

Software Collaboration

Teams working together on projects.

Repository

Project storage space where all changes to files are tracked.

Branch

Enables developers to work on different versions of the project.

Stage

Prepare for a commit by adding files to a staging area.

Commit

Captures staged changes as a snapshot to add to repository’s history.

Diff

Generate set of differences between 2 files or folders.

Patch

Apply a set of differences to update files.

Tools

Programming Tools
Name Description Example
Text editor For creating and editing source code Apache Netbeans IDE
SSH Secure Shell Client OpenSSH
Shell Access Access to the command line. Terminal
Git Distributed version control system. Git
Name Description Example

Create Remote Repository

# Create And Initialize Remote Repository #
git init --bare project.git

Create Local Repository

# Create New Project Folder If Applicable #
mkdir localproject
# Enter Project Folder #
cd localproject
# Initialize Local Repository As Working Folder #
git init

Add New File To Local Repository

# Create New File #
echo "Did you know that Ojambo.com has a donate button" > Readme.txt
# Start Tracking A Specific File (Stage) With Git #
git add Readme.txt
# Add A Message And Commit Changes With Git #
git commit -m "Initial Commit"

Connect Local Project To Remote Repository

# Add Remote Repository In Local Project #
git remote add origin remoteUser@remoteServer:project.git

Push Changes To Remote Repository

# Push Local Branch Changes To Remote Branch #
git push origin master

Modify Current File

# Edit File #
echo "and that it is found in the header bar." >> Readme.txt
cat Readme.txt
# Check Status #
git status

Compare Changes

# Compare Changes Within Git Repository #
git diff
# Compare Changes Using External Diff Tool #
git difftool

Optionally Set Default Diff Tool

# Modify Git Configuration To Set Meld As Diff Tool #
git config --global diff.tool meld

Download And Install Git

Download

Git can be downloaded from Distributed Version Control System. Then the downloaded file is extracted directly on the server or locally before individual files are uploaded if applicable.

Diffutils can be downloaded from GNU Diffutils. Then the downloaded file is extracted directly on the server or locally before individual files are uploaded if applicable.

Meld can be downloaded from Visual Diff And Merge Tool. Then the downloaded file is extracted directly on the server or locally before individual files are uploaded if applicable.

Explanation:

  1. The remote repository is created with bare because a working folder is not needed or it might be elsewhere such as for websites.
  2. The add command stages the desired files.
  3. The commit command will record a snapshot.
  4. The status command displays the state of the working folder and staging area.
  5. During the initial push, 2 branches are created, locally it is master and remote is origin.
  6. The git diff command is used to view changes made relative to the index (staging area for the next commit).
  7. The git difftool command is used to temporary configure the diff tool Git uses.
  8. The git config command is used to permanently configure the diff tool Git uses.

The remote repository is normally hosted on a remote location and accessed through SSH or a platform-specific method. During the commit, a message that clearly explains the changes made and why they were made helps future developers understand the context.

Git Remote Repository
Creation Of A Remote Git Repository

Git Local Repository And Branch
Creation Of A Local Git Repository And Branching

Git Add New File To Repository
Creation Of A New File, Remote, Commit And Push

Git Status Of Current Repository
Checking The Status After Modifying Current File

Git Diff Of Current Repository
Performing Diff Using Default Diff Tool And Difftool

Git Difftool Visual Diff Via Meld
Performing Visual Diff Using Difftool That Opened Meld


Usage

You can use any IDE or text editor and the command-line or a web browser (if applicable) to run Git commands. For this tutorial, Git was used for source code management. Git is cross-platform compatible (Unix, Linux, MacOS and Windows). Diff was used on text files and is also cross-platform compatible. Meld was used on text files and is also cross-platform compatible.

Open Source

Git is licensed under the GNU General Public License Version 2.0. The copyleft license comes with strict rules and requirements to ensure the software remains free and open-source. It allows commercial use, modification, distribution, and allows making derivatives proprietary, consult the license for more specific details.

Diffutils is licensed under the GNU General Public License Version 3.0 or later. The copyleft license comes with strict rules and requirements to ensure the software remains free and open-source. It allows commercial use, modification, distribution, and allows making derivatives proprietary, consult the license for more specific details.

Meld is licensed under the GNU General Public License Version 2.0 or later. The copyleft license comes with strict rules and requirements to ensure the software remains free and open-source. It allows commercial use, modification, distribution, and allows making derivatives proprietary, consult the license for more specific details.

Conclusion:

Git is a popular source code management system. Git is a distributed revision control system because every “working directory” contains the complete history and therefore revision tracking capabilities.

Git can work on remote servers or local machines to push committed changes and clone. The git difftool can can be used to choose your preferred diff tool.

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