post-merge hook in Git - Step-by-Step Execution

Process Flow - post-merge hook

Merge completes

↓

Git detects post-merge hook script

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Execute post-merge hook script

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Script runs commands (e.g., build, tests)

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Hook finishes

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Merge process ends

After a git merge finishes, Git runs the post-merge hook script if it exists, allowing automated tasks like rebuilding or testing.

Execution Sample

Git

#!/bin/sh
# post-merge hook example
echo "Merge completed"
make build
git status

This post-merge hook prints a message, runs a build, and shows git status after a merge.

Process Table

Step	Action	Command Run	Output	Result
1	Merge finishes	git merge branch	Merge successful	Merge completed
2	Detect post-merge hook	Check .git/hooks/post-merge	Script found	Prepare to run script
3	Run post-merge hook	echo "Merge completed"	Merge completed	Message shown
4	Run build command	make build	Build successful	Project rebuilt
5	Show git status	git status	On branch main nothing to commit	Status displayed
6	Hook ends	Script exits	No errors	Merge process complete

💡 Post-merge hook script finishes after running commands, merge process ends.

Status Tracker

Variable	Start	After Step 3	After Step 4	After Step 5	Final
Merge Status	Not merged	Merged	Merged	Merged	Merged
Hook Script Found	No	Yes	Yes	Yes	Yes
Build Status	Not built	Not built	Built	Built	Built
Git Status Output	N/A	N/A	N/A	On branch main nothing to commit	On branch main nothing to commit

Key Moments - 3 Insights

Why does the post-merge hook run only after the merge finishes?

Because the post-merge hook is triggered by Git only after the merge completes successfully, as shown in execution_table step 1 and 2.

What happens if the post-merge hook script is missing or not executable?

Git skips running the hook, so no commands run after merge; this is implied by step 2 where script detection is required.

Can the post-merge hook affect the merge result?

No, the hook runs after merge completes; it can run commands but cannot change the merge outcome, as seen in step 6.

Visual Quiz - 3 Questions

Look at the execution table, what command runs at step 4?

A git status

B echo "Merge completed"

C make build

D git merge branch

💡 Hint

Check the 'Command Run' column at step 4 in the execution_table.

At which step does Git detect the post-merge hook script?

A Step 2

B Step 3

C Step 1

D Step 5

💡 Hint

Look for 'Detect post-merge hook' action in the execution_table.

If the build command fails at step 4, what would change in the execution flow?

A The hook script would continue to step 5 normally

B The hook script would stop and not run git status

C Git would abort the merge

D The merge would be undone automatically

💡 Hint

Consider that post-merge hook runs commands sequentially; failure usually stops the script.

Concept Snapshot

post-merge hook:
- Runs automatically after a successful git merge
- Located in .git/hooks/post-merge
- Can run scripts like build, tests, or notifications
- Does not affect merge success
- Useful for automating post-merge tasks

Full Transcript

The post-merge hook is a script Git runs automatically after a merge finishes successfully. It is located in the .git/hooks directory and named post-merge. When a merge completes, Git checks if this script exists and is executable. If yes, Git runs it. The script can perform tasks like rebuilding the project, running tests, or showing status. The hook runs after the merge, so it cannot change the merge result. If the script is missing or fails, Git continues but the post-merge tasks may not complete. This hook helps automate steps you want to happen right after merging code.