git merge

The command used to integrate changes from one branch into another. Merging combines changes made in separate branches and creates a new commit that includes the changes from both branches.
Merging is a powerful feature of git that allows multiple developers to work on the same codebase simultaneously and combine their changes in a controlled and efficient way.

Git Branch Merge Demo

Create Git Repo

script

merge_branches() {
  local branch1="$1"
  local branch2="$2"
  
  # Validate branch names
  if ! git rev-parse --quiet --verify "$branch1" >/dev/null; then
    echo "Error: Branch '$branch1' does not exist."
    return 1
  fi
  
  if ! git rev-parse --quiet --verify "$branch2" >/dev/null; then
    echo "Error: Branch '$branch2' does not exist."
    return 1
  fi
  
  # Checkout branch2
  git checkout "$branch2"
  
  # Merge branch1 into branch2
  git merge "$branch1"
  
  # Check if merge was successful
  if [ $? -eq 0 ]; then
    echo "Merge completed successfully."
  else
    echo "Error: Merge failed."
    return 1
  fi
}

merge_branches $1 $2

~/proj1  >git init
Initialized empty Git repository in /Users/mchinnappan/proj1/.git/
~/proj1  (git)-[main]- >vi notes.md
~/proj1  (git)-[main]- >git add -A
~/proj1  (git)-[main]- >git commit -m init
[main (root-commit) d2fdd7b] init
 1 file changed, 2 insertions(+)
 create mode 100644 notes.md
~/proj1  (git)-[main]- >git log
commit d2fdd7b25355531e93dca4fcc6c5457d6596f7f8 (HEAD -> main)
Author: mohan chinnappan <mohan.chinnappan.n@gmail.com>
Date:   Tue May 16 09:29:44 2023 -0400

    init

Create branch dev

~/proj1  (git)-[main]- >git branch dev

List the branches

~/proj1  (git)-[main]- >git branch -a
  dev
* main

Edit notes.md in main branch

~/proj1  (git)-[main]- >vi notes.md
~/proj1  (git)-[main]- >git add -A
~/proj1  (git)-[main]- > cat notes.md
one
two

~/proj1  (git)-[main]- >git commit -m update_on_notes
[main 61fb145] update_on_notes
 1 file changed, 1 insertion(+)

Checkout dev

 ~/proj1  (git)-[main]- >git checkout dev
Switched to branch 'dev'
~/proj1  (git)-[dev]- >cat notes.md
one

merge from main to dev

~/proj1  (git)-[dev]- >bash git-branch-merge.sh main dev
Already on 'dev'
Updating d2fdd7b..61fb145
Fast-forward
 notes.md | 1 +
 1 file changed, 1 insertion(+)
Merge completed successfully.

Check merge

~/proj1  (git)-[dev]- >cat notes.md
one
two

How to list the merges done on the branch by an author

git log --merges --author="Ken"

Example - list the merges done by the author: mohan

git log --merges --author="mohan"

commit e307a67fec2e3af51d9361ef17f5c2153cbaf83a
Merge: c5c7a82 e6881af
Author: mohan chinnappan <mohan.chinnappan.n@gmail.com>
Date:   Fri May 5 18:10:43 2023 -0400

    Merge branch 'feature-0002'

commit c5c7a82be50820c548353f731881ef562c2c3aa5
Merge: b7353b8 a78f1a5
Author: mohan chinnappan <mohan.chinnappan.n@gmail.com>
Date:   Fri May 5 18:06:14 2023 -0400

    Merge branch 'feature-0002'

commit 50fa27fed0f56d1de8588aadd42db00cf522b24c
Merge: 972c964 6aff16d
Author: mohan-chinnappan-n <mohan.chinnappan.n@gmail.com>
Date:   Fri Feb 3 08:09:16 2023 -0500

    merged with feature-0001
3

Steps in performing merge

git checkout

~/git-demo  (git)-[feature-0002]- >git checkout main
Switched to branch 'main'

git merge


git merge feature-0002

Auto-merging iris.csv
Merge made by the 'ort' strategy.
 iris.csv | 1 +
 1 file changed, 1 insertion(+)

head iris.csv 
sepal_length,sepal_width,petal_length,petal_width,species
5.1,3.5,1.4,0.2,Iris-setosa
5.1,3.5,1.4,0.2,Iris-setosa
5.1,3.5,1.4,0.2,Iris-setosa
4.9,3,1.4,0.2,Iris-setosa
4.9,3,1.4,0.2,Iris-setosa
4.7,3.2,1.3,0.2,Iris-setosa
4.6,3.1,1.5,0.2,Iris-setosa
5,3.6,1.4,0.2,Iris-setosa
5.4,3.9,1.7,0.4,Iris-setosa

This command merges the changes from (feature-0002) into the current branch (main).
Before performing the merge, git checks whether there are any conflicts between the two branches. If there are conflicts, git will prompt you to resolve them manually.

Salesforce Development Notes