You have already posted this question,
here. Did the answers not satisfy you?
Anyway, if you are looking for the very basic linux command, you can do:
Code:
cd /bin
ls -1 > /path/to/any/dir/command_list.txt
where /path/to/any/dir must be substituted by a real path on your system, that is the place where you want to save the file. For a more complete command list, I think the answers to your previous post are fine!