How to list all available commands in unix like system?

Question

I want to list all available commands in a qnx 6.5.0 system. That is all commands that could be ran from the command line.

I think that listing all the contents of the PATH variable will do the job, but I also have to filter the non executable parts.

Is there a simple and easy way to that, using the most simple unix commands ?

NOTE: Our system uses korn shell and most of the unix commands are not included in the image.

Answer 1

Look into compgen. It's a built-in bash command that lists all command available.

Run this:
compgen -c

Answer 2

Try using the command:

compgen -ac