If you encounter the same problem as mine, which is not being able to use the tab key to choose from autocomplete in terminal (bash shell), I have a simple fix for you.
Bash-Autocomplete is a package that is installed by default on Antergos. So if you cannot use autocomplete feature in bash shell, make sure you have this package installed first. Of course, you probably already had it and still didn’t see any autocomplete feature in bash and that is why you are here. There are tons of completely different solutions on the Internet, most of them are from Ubuntu forum. The problem is that it is hard to find a working one for yourself. When I was checking out this problem on the Internet, I read a reply about running the right shell or not (bash vs sh). This was when I came up with an idea: make sure I am running bash. So, I typed bash and nothing happened. I then typed sudo bash and I was running terminal as root on this account, plus, the autocomplete worked! In conclusion, you simply just need to make sure that you are running your terminal in root permission, which can be done by command “sudo bash”. Below is the command you need:
# sudo bash