Client-side vs server-side hooks in Git - Visual Side-by-Side Comparison

Process Flow - Client-side vs server-side hooks

Start: Git Action Triggered

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Run Client-side Hook Script

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Hook Passes?

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Run Server-side Hook Script

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Hook Passes?

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Action Proceeds

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Reject Action

When a Git action happens, client-side hooks run first on your computer. If they pass, server-side hooks run on the server. If all hooks pass, the action completes.

Execution Sample

Git

# Client-side pre-commit hook
#!/bin/sh
# Check for TODO comments
if git diff --cached | grep TODO; then
  echo "Remove TODOs before commit"
  exit 1
fi

# Server-side pre-receive hook
#!/bin/sh
while read oldrev newrev refname; do
  if [ "$refname" = "refs/heads/main" ]; then
    # Reject force pushes
    if [ "$oldrev" != "0000000000000000000000000000000000000000" ] && ! git merge-base --is-ancestor "$oldrev" "$newrev"; then
      echo "Force pushes to main are not allowed"
      exit 1
    fi
  fi
done
exit 0

This example shows a client-side pre-commit hook that blocks commits with TODO comments, and a server-side pre-receive hook that rejects force pushes to main branch.

Process Table

Step	Hook Type	Action Triggered	Hook Script Runs?	Hook Result	Next Step
1	Client-side	git commit	Yes	No TODO found, pass	Run server-side hooks
2	Server-side	Receive push	Yes	No force push detected, pass	Action proceeds
3	Client-side	git commit	Yes	TODO found, fail	Reject commit
4	Client-side	git commit	Yes	No TODO found, pass	Run server-side hooks
5	Server-side	Receive push	Yes	Force push detected, fail	Reject push

💡 Execution stops when a hook fails or all hooks pass allowing the action.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5
Commit Content	Initial	No TODO	No TODO	Has TODO	No TODO	No TODO
Push Type	Initial	N/A	Normal push	N/A	N/A	Force push
Hook Pass Status	N/A	Pass	Pass	Fail	Pass	Fail

Key Moments - 3 Insights

Why does the commit get rejected even before reaching the server?

Because the client-side pre-commit hook found TODO comments and failed, as shown in execution_table row 3.

What happens if the client-side hook passes but the server-side hook fails?

The push is rejected by the server-side hook, as shown in execution_table row 5, stopping the action on the server.

Are server-side hooks run for local commits?

No, server-side hooks run only on the server during push or receive actions, not on local commits (see execution_table rows 1 and 3).

Visual Quiz - 3 Questions

Look at the execution table, what is the hook result at step 3?

A No TODO found, pass

B TODO found, fail

C Force push detected, fail

D No force push detected, pass

💡 Hint

Check the 'Hook Result' column in execution_table row 3.

At which step does the server-side hook reject the action?

A Step 2

B Step 3

C Step 5

D Step 1

💡 Hint

Look for 'Force push detected, fail' in the 'Hook Result' column.

If the client-side hook finds no TODOs, what is the next step?

A Run server-side hooks

B Reject commit immediately

C Skip server-side hooks

D Abort the git action

💡 Hint

See execution_table row 1 'Next Step' column.

Concept Snapshot

Client-side hooks run on your computer before actions like commit.
Server-side hooks run on the server during push or receive.
Client-side hooks can block bad commits early.
Server-side hooks enforce rules centrally.
If any hook fails, the action is stopped.
Hooks run in order: client-side first, then server-side.

Full Transcript

When you perform a Git action like commit or push, Git checks for hooks to run. First, client-side hooks run on your local machine. For example, a pre-commit hook can check your code for TODO comments and stop the commit if any are found. If the client-side hooks pass, and you push to a remote repository, server-side hooks run on the server. For example, a pre-receive hook can reject force pushes to the main branch. If any hook fails, Git stops the action and shows an error. This process helps catch problems early on your computer and enforce rules on the server. The execution table shows steps where hooks run and their results, helping you understand when and why actions proceed or stop.