constant FILE_EXIST

drupal_verify_install_file in drupal/core/includes/install.inc

Verifies the state of the specified file.

install_check_requirements in drupal/core/includes/install.core.inc

Checks installation requirements and reports any errors.

install_check_translations in drupal/core/includes/install.core.inc

Checks installation requirements and reports any errors.

install_configure_form in drupal/core/includes/install.core.inc

Form constructor for a form to configure the new site.

system_requirements in drupal/core/modules/system/system.install

Test and report Drupal installation requirements.

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