Merge branch 'RULES_E3-module_name_check-use_grep_-q' into 'master'

RULES_E3/module_name_check: use `grep -q`

See merge request e3/e3-require!6

configure/modules/RULES_E3

@@ -73,7 +73,7 @@ conf: module_name_check
 
 ## We should check that the module name satisfies a few conditions before we go on.
 module_name_check:
-ifneq ($(shell echo $(E3_MODULE_NAME) | grep '^[a-z_][a-z0-9_]\+$$' &> /dev/null; echo $$?),0)
+ifneq ($(shell echo $(E3_MODULE_NAME) | grep -q '^[a-z_][a-z0-9_]\+$$' ; echo $$?),0)
 	$(error E3_MODULE_NAME '$(E3_MODULE_NAME)' is not valid. It should consist only of lowercase letters, numbers, and underscores.)
 endif