(sc_file_system): New target.

(syntax-check-rules): Add it.

Makefile.maint

@@ -72,6 +72,7 @@ syntax-check-rules = \
   sc_changelog \
   sc_dd_max_sym_length \
   sc_error_exit_success \
+  sc_file_system \
   sc_prohibit_atoi_atof \
   sc_prohibit_jm_in_m4 \
   sc_space_tab \
@@ -137,6 +138,13 @@ sc_error_exit_success:
 	  { echo '$(ME): found error (EXIT_SUCCESS' 1>&2;		\
 	    exit 1; } || :
 
+sc_file_system:
+	@grep -i 'filesystem'						\
+	     $$(cvsu --list | grep -vEf .x-$@ ) &&			\
+	  { echo '$(ME): found use of "filesystem";'			\
+	    'rewrite to use "file system"' 1>&2;			\
+	    exit 1; } || :
+
 # FIXME: warn about definitions of EXIT_FAILURE, EXIT_SUCCESS, STREQ
 
 # Each nonempty line must start with a year number, or a TAB.