Git合并分支时如何保留指定文件的特定内容，其余复用另一分支？

Absolutely! You can achieve this conditional merge behavior in Git using custom merge drivers (to handle content preservation) and Git hooks (to manage filename cleanup). Let’s walk through the setup step by step, tailored to your exact scenario:

Core Idea #

When merging between master and dev:

• Merging into dev: Keep xxx-dev.txt, preserve its ID=02 line, and replace all other content with what’s in master’s xxx-master.txt.
• Merging into master: Keep xxx-master.txt, preserve its ID=01 line, and replace all other content with what’s in dev’s xxx-dev.txt.

Step 1: Create a Custom Merge Script #

This script will handle the content merging logic, preserving the target branch’s ID line while pulling other content from the source branch.

1. Create a directory for Git scripts (if you don’t have one):

   mkdir -p ~/.git/scripts
   

2. Create a script named merge-preserve-id-name.sh in this directory with the following content:

   #!/bin/bash
   
   # Get the target branch (the branch we're merging INTO)
   TARGET_BRANCH=$(git rev-parse --abbrev-ref HEAD)
   OURS="$1"    # Current branch's file (target branch)
   BASE="$2"    # Common ancestor file
   THEIRS="$3"  # Source branch's file (the branch we're merging from)
   RESULT="$4"  # Output file for merged content
   
   if [ "$TARGET_BRANCH" = "dev" ]; then
       # Preserve ID=02 from dev's file, take rest from master's file
       PRESERVED_ID=$(grep "ID=02" "$OURS")
       # Filter out any ID lines from the source branch's content
       grep -v "ID=" "$THEIRS" > "$RESULT"
       # Append the preserved ID line
       echo "$PRESERVED_ID" >> "$RESULT"
   elif [ "$TARGET_BRANCH" = "master" ]; then
       # Preserve ID=01 from master's file, take rest from dev's file
       PRESERVED_ID=$(grep "ID=01" "$OURS")
       grep -v "ID=" "$THEIRS" > "$RESULT"
       echo "$PRESERVED_ID" >> "$RESULT"
   else
       # Fallback to Git's default merge if not merging into master/dev
       git merge-file "$OURS" "$BASE" "$THEIRS" > "$RESULT"
   fi
   

3. Make the script executable:

   chmod +x ~/.git/scripts/merge-preserve-id-name.sh
   

Step 2: Configure Git to Use the Merge Driver #

Add the custom merge driver to your Git config. Open ~/.gitconfig or your project’s .git/config file and add:

[merge "preserve-id-name"]
    name = Preserve target branch's ID and filename during merge
    driver = ~/.git/scripts/merge-preserve-id-name.sh %O %A %B %L

• %O: Path to the common ancestor file
• %A: Path to the target branch’s file
• %B: Path to the source branch’s file
• %L: Path to the merged result file

Step 3: Assign the Driver to Your Files #

Create a .gitattributes file in your project root to tell Git which files to apply this driver to:

xxx-*.txt merge=preserve-id-name

This matches both xxx-master.txt and xxx-dev.txt.

Step 4: Clean Up Extra Files with a Post-Merge Hook #

Since Git will treat xxx-master.txt and xxx-dev.txt as separate files by default, we need to delete the unwanted file after merging.

1. Create a post-merge hook in your project’s .git/hooks directory:

   #!/bin/bash
   
   TARGET_BRANCH=$(git rev-parse --abbrev-ref HEAD)
   
   if [ "$TARGET_BRANCH" = "dev" ]; then
       # Remove master's file if it exists after merging into dev
       if [ -f "xxx-master.txt" ]; then
           git rm xxx-master.txt
           git commit -m "Cleanup: Remove xxx-master.txt after merging into dev"
       fi
   elif [ "$TARGET_BRANCH" = "master" ]; then
       # Remove dev's file if it exists after merging into master
       if [ -f "xxx-dev.txt" ]; then
           git rm xxx-dev.txt
           git commit -m "Cleanup: Remove xxx-dev.txt after merging into master"
       fi
   fi
   

2. Make the hook executable:

   chmod +x .git/hooks/post-merge
   

Testing the Setup #

• Merge master into dev: Git will update xxx-dev.txt to use master’s content except for ID=02, then automatically delete xxx-master.txt.
• Merge dev into master: Git will update xxx-master.txt to use dev’s content except for ID=01, then automatically delete xxx-dev.txt.

Notes #

• Double-check branch names in scripts (if your branches use uppercase like Master or Dev, adjust the script accordingly).
• If your ID lines have more specific formatting, tweak the grep patterns to match exactly.

内容的提问来源于stack exchange，提问作者Traceur