Auto search/replace in text files

I require a simple program to search and replace text in text/ini files during system startup without any user interaction. The search/replace fields and any other relevant details and the file to edited need to be contained in an external ini file. The program needs to be able to use wildcards (and regular expressions if possible), and must also allow text to be replaced with the current system date/time (in a variety of formats eg. d-mmm, mmm-yy, m/d/yy, mmm-yy).