[Help-bash] Is there a convenient function that return what is printed after typing <TAB>?

[Peng Yu]

Hi,

<TAB> can print a number of candidate commands. Is there a command
that can take the partial command and print all the candidates (so
that the output can feed to another program)? (This is not a difficult
problem to program from scratch if I just want to get the candidates
from PATH, but it is not obvious to how to get all the candidates set
by custom bash-completion.)

-- 
Regards,
Peng