Introduction

• git diff command is used to view changes in files between various states in your Git repository.
• It shows the differences between the working directory and the staging area, helping you to review the changes before committing.
• It is useful for code reviews and debugging.

• When to use git diff ?
  • To check the differences before committing changes.
  • To see changes between specific commits or branches.
  • To analyze conflicts during a merge process.

How to use git diff ?

• View changes in files:
  • git diff
• The command will show the following:
  • 
• Explanation of the Output:
  • diff --git a/aaa.txt b/aaa.txt
    • This line indicates that the file aaa.txt is being compared.
      • a/aaa.txt The file version from the staging area (previous state).
      • b/aaa.txt The file version from the working directory (current state).
  • index d9981b9..dced72b 100644
    • d9981b9 and dced72b are Git's internal hashes for the content before and after the change.
    • 100644 is the file permission mode.
  • --- a/aaa.txt
    • This marks the "old" version of the file.
  • +++ b/aaa.txt
    • This marks the "new" version of the file.
  • @@ -1 +1,2 @@
    • The -1 means starting at line 1 of the old version.
    • The +1,2 means starting at line 1 of the new version, with 2 lines in total.
  • -this is aaa first statement
    • The line prefixed with - indicates a line from the old version that was removed.
  • +this is aaa first statement
    +this is aaa second statement
    • The lines prefixed with + indicate lines added in the new version.
  • \ No newline at end of file
    • This message means that the file does not end with a newline character.

Different ways to use git diff ?

1. View Unstaged Changes:
   • git diff
   • Shows changes between the working directory and the staging area.
   • Useful to check modifications before staging.
2. View Staged Changes:
   • git diff --cached
   • Shows differences between the staging area and the last commit.
   • Useful to review changes before committing.
3. Compare Working Directory with Last Commit:
   • git diff HEAD
   • Displays all changes since the last commit.
   • Useful to see all modifications, whether staged or not.
4. Compare Specific Commits:
   • git diff commit1 commit2
   • Compares the differences between two commits.
   • Useful for tracking changes over time.
5. View Changes for a Specific File:
   • git diff filename.txt
   • Shows modifications made to a specific file.
   • Useful for focused code reviews.
6. Compare Staged and Unstaged Changes for a File:
   • git diff filename.txt
git diff --cached filename.txt
   • Useful to compare what's modified but not staged vs. staged but not yet committed.
7. Show Changes in a Specific Commit:
   • git diff commit-hash
   • Displays changes introduced by a specific commit.
   • Useful to understand the impact of a particular commit.
8. Compare Changes Between Branches:
   • git diff branch1 branch2
   • Compares the differences between two branches.
   • Useful to check what will be merged or needs resolution.
9. Ignore Whitespace Changes:
   • git diff -w
   • Ignores whitespace differences, focusing only on actual code changes.
   • Useful for cleaner comparisons.
10. Show Summary of Changes:
    • git diff --stat
    • Shows a summary of the number of files changed, and lines added/removed.
    • Ideal for a quick overview of modifications.