Find location where process started from on linux

If I have output from ps like the following, is there any way to determine where 'blah' is on the file system? For my particular situation, the -p specifies which port the application should run on.

user 22913 22470  0 09:58 ?        00:00:06 ./blah -p 12345

My question is basically whether or not it is possible to find the location of an executable given the PID or port of the application. The distro being used is Redhat.

Do any of these give information?

ps -ef

ps -eLf

ps axms

Or maybe

ps -o cmd= -p $PID

This might be more useful:

readlink -f /proc/$PID/exe

?

Like Bart suggested,

readlink -f /proc/$PID/exe

shoud give you your answer.