"alert()" creates a window with specified text and waits
until user closed the window (by pressing any key).
local alert = require("alert")
"alert.lua" is pure Lua module, compatible with Lua 5.3, 5.2, 5.1, and LuaJIT.
It does not depend on any C library, all it needs is "os.execute()" and "io.popen()".
It works on Linux, Mac OS X, Windows and Cygwin.
"alert()" performs its task by invoking terminal emulator
and executing shell command "echo YourMessage" inside it:
1) "CMD.EXE" (Windows Command Prompt) is used on Windows and Cygwin;
2) "Terminal.app" is used on Mac OS X;
3) any of 17 supported terminal emulators (if found to be installed on your system)
is used on Linux.