cmake: cmake < 2.6 doesn't know FILE(STRINGS ...)

CMakeLists.txt

@@ -130,12 +130,24 @@ ADD_DEPENDENCIES(${PROJECT_AWE_NAME} generated_headers)
 IF(GENERATE_MANPAGES)
 
     MACRO(a_file_match infile regex result_var)
-        FILE(STRINGS ${infile} matches REGEX ${regex} LIMIT_COUNT 1)
-        IF(matches)
+        IF(CMAKE_MAJOR_VERSION EQUAL 2 AND CMAKE_MINOR_VERSION LESS 6)
+            # cmake < 2.6 doesn't know FILE(STRINGS ...)
+            EXECUTE_PROCESS(COMMAND ${GREP_EXECUTABLE} -l ${regex} ${infile}
+                            RESULT_VARIABLE exit_code
+                            OUTPUT_QUIET)
+            IF(exit_code EQUAL 0)
                 SET(${result_var} TRUE)
             ELSE()
                 SET(${result_var} FALSE)
             ENDIF()
+        ELSE()
+            FILE(STRINGS ${infile} match REGEX ${regex} LIMIT_COUNT 1)
+            IF(match)
+                SET(${result_var} TRUE)
+            ELSE()
+                SET(${result_var} FALSE)
+            ENDIF()
+        ENDIF()
     ENDMACRO()
 
     # find .c files exporting lua functions

awesomeConfig.cmake

@@ -23,6 +23,7 @@ ADD_DEFINITIONS(-std=gnu99 -ggdb3 -fno-strict-aliasing -Wall -Wextra
 
 # {{{ Find external utilities
 FIND_PROGRAM(CAT_EXECUTABLE cat)
+FIND_PROGRAM(GREP_EXECUTABLE grep)
 FIND_PROGRAM(GIT_EXECUTABLE git)
 FIND_PROGRAM(LUA_EXECUTABLE lua)
 # programs needed for man pages