This article is from the FAQ, by with numerous contributions by others.
By default, the executable generated from a BETA program called test.bet is
called test. Depending on your UNIX installation's defaults and your own
environment variables, attempts to execute the BETA program by typing test
may, however, result in the standard system program test being executed
instead. To avoid the problem, just type ./test instead of test.
Similar problems can arise with other, existing UNIX commands.
[Note: This is a typical beginner's problem, not related to the BETA
language or the BETA environment as such.]