DevOps Classroomnotes 11/Sep/2022

Exercises

• Create a new folder anywhere in your system and make it a git repo
• Create 3 folders and check for status
• now add a file in first folder and then execute git status
• add this change to staging area
• create one more file in second folder and add this change also to staging area
• Now commit the change
• Draw a tree like what we have done in the class git log --oneline
• Now create two files in third folder, add them to staging area and now remove one file from staging area and create 2 commit.
• Update your tree
• now add the file which you moved from staging area to working tree back to staging ared and then create a third commit
• Now create two files each in three folders add all of them to staging area
• Clean the above changes as if you have not done any changes after 3 commit.

Some popular but correct opinions

• Git is a Stupid Content Tracker
• Linus Torvalds has a built a new file system which can track contents
• Lets understand how git works
• When we initialize git repository
  • .git folder gets created
  • HEAD pointer points to a default reference which is master
  • Reference will point to a specific commit id
• Create a first commit on some folder after initalization.
  
• Now lets use a plumbing command git cat-file
  • git cat-file -t shows the type
  • git cat-file -p shows the contents
• Git uses SHA-1 Hash to store objects.
• Git has following object types
  • tree => folder
  • blob => file
  • commit
• Lets find out the type and contents of commit id
  
• Now lets find the contents of tree
  
• Lets find the contents of file i.e. blob main.py
  
• main.py is empty
• Now lets some content and create a second commit
• please refer video for the rest of images on how git works.

Git Branches

• Git by default create a branch which is called as master
• Branch will point to a latest commit done in it.
• To create a new branch from existing branch git branch <branch-name>
  
• Now lets make some changes in rel_1.0_siemens, to do this HEAD should be pointing towards rel_1.0_siemens for this we use checkout
  
• Now lets add some changes as discussed in the class
  
  
• Next Steps:
  • A change done in the master branch should be made available to both siemens and ge branch
  • A commit in ge branch should also be applied to siemens branch
  • Adding multiple users i.e.Remote Repository
    • pull
    • fetch
    • push
    • remote branches
    • remote repos
    • origin
  • All the changes done for siemens and ge to be merged to common branch
  • The above activities can be address
    • merge
    • rebase
    • cherry pick
    • merge – conflicts