Getting Flex's trace() to appear on the command prompt

Flex's trace(), afaik, will not output to stdout or the command prompt. However you can have it output to a log file in real time. This means you can use the Unix tail command to achieve the equivalent.

1. Create a file as shown below and name it mm.cfg

ErrorReportingEnable=1
TraceOutputFileEnable=1
TraceOutputFileName=c:\log-directory-path\flashlog.txt

2. Put it in the following directories:

OS X - MacHD:Library:Application Support:Macromedia:mm.cfg
Windows XP - C:\Documents and Settings\username\mm.cfg
Windows 2000 - C:\mm.cfg
Linux - home/username/mm.cfg

3. Track the contents of flashlog.txt via tail

tail -f flashlog.txt

UPDATE: With Flash Player 9 Update, it is no longer possible to change the default location of flashlog.txt and it will always be found under Application Data\Macromedia\Flash Player\Logs\ instead. See here for details.