Question

How to make CLI password masking in Lua? E.g. when I write password it changes into asterisk or nothing is shown at all? I need platform-independent solution as my script will be used in Java application.

Answer 1

In plain Lua, the answer is simple: you can’t.

Since Lua is written in ANSI C you can not get characters from the command line without having to press enter. You can however make use of bindings to libraries like curses.lua which comes with luaposix.

Or if you can assume you’ll have an ANSI VT, you can resort to a hack like this:

io.write("\027[s") -- save cursor position
l=io.read()
io.write('\027[u',('*'):rep(#l),"\n") -- rewind to where we were, and fill with the correct amount of stars
print("pst, I got", l, "but don't tell anyone!")

More info about ANSI terminal control

But if it’ll be used for a Java application, why not use Java for the password prompt. I guess their support and control of the cli would be better and cross-platform…