pitfalls.txt

It may be that you can't execute files from the current
directory. Probably you're using bash and probably your
file /etc/profile contains a line
  PATH="/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games"

This misguided security paranoia setting of the path should be
changed for normal users to

  PATH=".:/usr/local/bin:/usr/bin:/bin"

[Unless you'r keen on playing hunt_the_wumpus from a text console,
then you must keep both game directories
  PATH=".:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games"]

Anyway you can fix your PATH for a session with
set PATH=".:$PATH"

Officially you should find out your shell, and patch your personal
configuration. Unfortunately your shell is probably bash and its
documentation is unwieldy.

If you're in despair because you can't get back previous commands
with arrow up, check out rlwrap. Usage: rlwrap yourforth.