Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.

ckeditor5_requirements in core/modules/ckeditor5/ckeditor5.install
Implements hook_requirements().
ckeditor_requirements in core/modules/ckeditor/ckeditor.install
Implements hook_requirements().
file_requirements in core/modules/file/file.install
Implements hook_requirements().
image_requirements in core/modules/image/image.install
Implements hook_requirements() to check the PHP GD Library.
install_check_requirements in core/includes/install.core.inc
Checks installation requirements and reports any errors.
install_verify_requirements in core/includes/install.core.inc
Verifies the requirements for installing Backdrop.
node_requirements in core/modules/node/node.module
Implements hook_requirements().
requirements1_test_requirements in core/modules/simpletest/tests/requirements1_test.install
Implements hook_requirements().
simpletest_requirements in core/modules/simpletest/simpletest.install
Implements hook_requirements().
system_get_requirements in core/includes/install.inc
Get run-time requirements and status information.
system_requirements in core/modules/system/system.install
Implements hook_requirements().
telemetry_requirements in core/modules/telemetry/telemetry.install
Implements hook_requirements().
unicode_requirements in core/includes/unicode.inc
Returns Unicode library status and errors.
update_check_requirements in core/update.php
Checks update requirements and reports errors and (optionally) warnings.
update_extra_requirements in core/update.php
Returns and stores extra requirements that apply during the update process.
update_fix_requirements in core/includes/update.inc
Perform Drupal 7.x to Backdrop 1.x updates that are required for update.php to function properly.
update_requirements in core/modules/update/update.install
Implements hook_requirements().
update_script_test_requirements in core/modules/simpletest/tests/update_script_test.install
Implements hook_requirements().