composer.json在composer update上执行

Question

I have one questions related to composer: Please look at following directory structure in laravel.

laravel
|-- app
|-- bootstrap
|-- config
|-- composer.json
|-- composer.lock
`-- vendor
    |-- composer
    |-- danielstjules
    |   |-- composer.json
    |   `-- and other files
    |-- dnoegel
    |   |-- composer.json
    |   `-- and other files
    |-- doctrine
    |   |-- composer.json
    |   `-- and other files
    `-- doctrine
        |-- composer.json
        `-- and other files

and i am using composer to manage dependency. On my directory structutre, there are many files of composer.json, mainly in vendor folder,in all sub-folder of vendor directory has a composer.json file.

then my question is : if i exceute composer update command from my app folder like :

vishal@vishal-desktop /var/www/laravel $ composer update

1) which composer.json will be updated only of app diectory? or

2) all composer.json of all subfolder in /var/www/laravel folder?