DevOps Classroomnotes 30/Apr/2022

Git Contd…

• In the last session we discussed about merge where a new commit was created with two parents, this is generally referred as three-way-merge
• Cherry picking was done on once commit i.e. we added one commit from one branch to other branch (without merging)
• Cherry picking can also done on sequence of commits
• Lets create a feature_1003 branch with 4 commits in it
• Now if we merge the changes back to rel_tata_v1.0, by default it creates a fast-forward merge, if your organization follows a practice that whenever you merge we need a commit for that, we can create an extra commit (three way merge) by adding (–no-ff)
  
  
• Now lets move to the feature_1003 branch
  
• Now we want all of this 4 commits on rel_wipro_v1.0, so lets cherry-pick range of commits
  
  
  

Special Characters used in Git

• In Git we would be using
• Tilde ~:
  • to go back a number of generations
• Caret ^
• double dot ..

Exercise:

• Create a new git repository
• Try to create a branch and create a situation for merge conflict
• Try to create a situation for merge without a conflict.

Rebase

• Consider the following situation
  
• We need the changes done in master branch after feature branch creation to be part of feature branch, the best way to do it would be as shown graphically below
  
• Git rebase can exactly do this.
• Consider the following situation
  
• Now we want changes of master to be part of feature_branches history
  
• Now execute git rebase <source branch>
  
  

Lets visit the Three areas of Git (Local Repo)

Manipulating History

• Mistakes in previous commit message
  • situation
    
  • solution
    
    
    
• reflog:
  • Git keeps track of the updates to the tip of branch using a mechanism called as reference logs or reflog
    
• RESET:
  • Git reset has three modes: soft, mixed and hard
  • Soft Reset:
    • consider the following changes
      
    • Now lets soft reset to second commit
      
      
    • Changes are not lost
  • Hard Reset:
    • Consider the following changes
      
      
    • Changes are lost
  • Mixed Reset:
  • Consider the following changes
    
  • Changes are moved to the working tree (unstaged)
    
  • Changes are not lost