Hi, I would like to be able to replace environment variables specified in config file values. For example I would like to use the env. var. (BOOST_PATH=c:\Boost) to expand the following file1=${BOOST_PATH}\include into this: file1=c:\Boost\include So I can then parse the value (c:\Boost\include) as a boost::filesystem::path. It seems like I want something similar to the extra parser for command-line options, but it doesn't seem to be possible for the config file parser. Do you have any ideas how to accomplish this? Also, is there a parser in program_options or property_tree that can parse "Java Property"-style property files, such as # My comment here cache=1kb file=c:/autoexec.bat Thanks, Chris