About

This is a way of running Lua with a mouse click on Linux, macOS and Windows. It supports a way to detect if ran from a file browser or command line, arguments, shortcuts on Windows (with arguments) and a nice way of showing errors.

It works by simply downloading the Lua executable with Shell or Batch from the internet. By default, the scripts download files to ./data/* but you can also set it to write to $HOME/.appexample on Unix or%appdata%\appexample on Windows if you want.

DownloadFile helper function

# bash
# Uses wget or curl
DownloadFile "https://foobar.com/baz" "baz"

:: batch
:: Uses curl or powershell
call:DownloadFile "https://foobar.com/baz.exe" "baz.exe"

The DownloadFile function on Windows will use curl, powershell or Windows Script Host depending on what's available. It should work on windows 2000 and up, but beware of the lack of https support on old versions of windows.

When downloading an executable it's good practice to run validation afterwards to make sure it works. For example, if lua_downloaded_and_validated doesn't exist download luajit.exe, check if the exit code is correct by running os.exit and if successful write lua_downloaded_and_validated to the same directory indicating that it's been downloaded and validated. This is what the example scripts do.

How is it possible to allow Lua in Shell and Batch?

Both of the scripts use some syntax to allow writing Lua code at beginning of each script. Batch uses the following:

::_::BATCH_PROGRAM=[[
...
goto:eof
rem ]]

Which requires goto labels in Lua to be valid. This can be replaced with the following if Lua 5.1 is desired.

rem = nil BATCH_PROGRAM=[[
...
goto:eof
rem ]]

The Shell version uses the following:

#!/bin/sh
SHELL_PROGRAM=[=[
...
exit 0
]=]

Which looks a bit more natural.

These hacks are not strictly nesseceary as you change the script to download an external Lua script and just execute that instead.

Why not powershell or WSH on Windows?

I use Batch because it has a significant faster startup time than Powershell. Windows script host (.js or .vb) is fast but has some limitations when it comes to being executed from command line vs explorer.