@nina_kali_nina unixemu is a system program (basically a kernel module), not a user program. It only implements Unix API compatibility, and not a shell environment. A Unix shell environment with development tools can be found at http://www.chokanji.com/developer/download.html (specifically selfenv.bin). Once you've installed it, you can run /SYS/ucli from the console to get a Unix shell, although it's a bit limited
@andreww thank you for the explanation! This is what I expected. Kind of sad they didn't put it on the CD, there was still plenty space left.
Also, curiously, the 4.5 release looks just like 1.1 release https://www.os-museum.com/brightv/brightv.htm
p.s. Thank you for your OS archival and museum efforts :)