Gii in Yii2 doesn't work, what's wrong?

Question

Yii

I go to Gii, click Preview, then the Generate button. A pink window pops up saying "There was something wrong when generating the code. Please check the following messages."
Below it is a black window
Generating code using template "/var/www/html/sitte/vendor/yiisoft/yii2-gii/generators/ module/default"...
generating modules/admin/Module.php
Unable to create the directory '/var/www/html/sitte/modules/admin'.
generating modules/admin/controllers/DefaultController.php
Unable to create the directory '/var/www/html/sitte/modules/admin/controllers'.
generating modules/admin/views/default/index.php
Unable to create the directory '/var/www/html/sitte/modules/admin/views/default'.
done!
What's the matter ?

Answer 1

set the permissions on the folder
sudo chmod -R 1777 var/www/html/sitte
but this is not safe (sorry for bad advice)
I think you need to figure out what rights gii requires to run scripts

Answer 2

Check directory permissions