When to Use `composer update` vs. `composer install`?

Exploring the Differences Between composer update and composer install

Composer, a popular PHP dependency manager, offers two key commands: composer update and composer install. While they share a common goal of managing dependencies, they serve distinct purposes and operate in different ways.

Composer Update

When you run composer update, it examines the composer.json file and compares it to the installed packages. For each dependency declared in composer.json, it determines the latest available version and installs or upgrades to it. This behavior is particularly useful during development when you want to keep up with the latest updates for your project's dependencies.

Detailed steps performed by composer update:

• Reads composer.json.
• Removes installed packages that are no longer specified in composer.json.
• Checks for the latest versions of required packages.
• Installs the latest package versions.
• Updates composer.lock to reflect the newly installed versions.

Composer Install

In contrast, composer install doesn't update any packages. Instead, it relies on the composer.lock file, which is created and managed by composer update. It reads this file and installs all the dependencies specified within it. This ensures that the application's dependencies remain consistent across different environments, such as development and production.

Steps performed by composer install:

• Checks if a composer.lock file exists; if not, composer update is run to create it.
• Reads composer.lock.
• Installs the packages listed in composer.lock.

When to Use Each Command

• Composer update: Use this command during development to keep dependencies up-to-date and ensure you're working with the latest versions.
• Composer install: Use this command when deploying your application to a production environment or when setting up a new testing environment. It ensures that the installed dependencies match those specified in the composer.lock file, creating a consistent application environment.

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