Logging from multiple scripts

I have a web app and a CLI app which runs as a cron job and I am looking to have both log to a single file. I was looking at the error_log() and Pear::Log package. I am specifically looking to do this to a file and not a database since this needs to be a fairly self-contained app. Would one of the 2 ways I mentioned work for what I want? Is there a better way to do it? Thanks for the help. --Aaron