update

Learn per-branch checks with the update hook.

What Is the update Hook?

The `update` hook runs separately for each reference update on the server. The script receives the reference name and the old and new object IDs as arguments. This makes it possible to apply different rules to different branches.

#!/bin/bash
refname="$1"
echo "$refname"

Checking Branches with Arguments

The `update` hook receives the reference name as its first argument, the old object ID as its second argument, and the new object ID as its third argument. Branch references begin with `refs/heads/`. The script can reject an update that violates a rule by returning a non-zero exit status.

refname="$1"
if [[ "$refname" == "refs/heads/main" ]]; then
  exit 1
fi

Exercise Reject an Update to the Main Branch

Create an `update` hook script. Assign the reference name from the first argument to the `refname` variable. If the reference is `refs/heads/main`, print an error message and exit with status 1. Allow updates to other branches.

Show example solution

#!/bin/bash
refname="$1"
if [[ "$refname" == "refs/heads/main" ]]; then
  echo "Ana dal güncellemesi yasak" >&2
  exit 1
fi
echo "Güncellemeye izin verildi"

Test yourself

What is the main difference between the update hook and pre-receive?
- It runs after the push operation finishes
- It only runs on the local computer
- It runs separately for each reference update
- It only checks file names
Show answer

It runs separately for each reference update — `update` evaluates each reference update separately, making branch-specific rules easier to implement.

Read an update Hook Argument

#!/bin/bash
refname="$_____"____

Show answer

#!/bin/bash
refname="$_____"1

Match the update Hook Arguments

$1

Reference name
$2

Old object ID
$3

New object ID
exit 1

Rejects the update

Next lesson: Summary - Custom hooks

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