> printf(arg) looks just like the txt file,this is a good thing
If Dave were here he would point out this: http://en.wikipedia.org/wiki/Format_string_attack
If I understand you correctly, you know how to read from files, you just want to store the switches from the file in argv[]. Then:
1. Parse the file for switches, storing them in a temporary string.
2. argc equals how many switches there were.
3. for each switch s to argc, use strncpy to put the switch in argv[s]