[CMake] multiple add_custom_command solution

[Micha Renner]

I have a program prog filename, that generates an output to stdout. To
collect data in a file one uses
prog filename > result.txt

In a CMake-script I have list of 5 files which should processed by the
program

SET(_moduleList name1 name2 name3 name4 name5)

FOREACH(_module ${_moduleList})

  ADD_CUSTOM_COMMAND(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${_module}.dummy
      COMMAND cmake -E touch {CMAKE_CURRENT_BINARY_DIR}/${_module}.dummy
      COMMAND prog ${_module}.txt >> tm16.txt
      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/${CMAKE_BUILD_TYPE}
      COMMENT "-- done") 
	
     LIST(APPEND _result ${CMAKE_CURRENT_BINARY_DIR}/${_module}.dummy)

ENDFOREACH(_module ${_moduleList})
	  
ADD_CUSTOM_TARGET(tProcess ALL DEPENDS ${_result}) 

The main disadvantage of this is
- The target works correct only if tm16.txt does not exist before it
  runs.

Does someone knows a better solution.

Micha