How to list directory (folder) contents in Lua?

Lua has very limited file system support in its standard library, because it is largely a wrapper around the standard C library, which itself has lackluster filesystem support. os.rename, os.remove, os.tmpname, io.tmpfile are all direct analogues to their standard C counterpart.

As pointed out, io.popen is available¹ to POSIX systems (popen), as well as Windows (popen), which can be used to invoke platform-dependent tools.

local lfs = require 'lfs'
for entry in lfs.dir '/sys' do
    print(entry)
end

.
..
kernel
power
class
devices
dev
hypervisor
fs
bus
firmware
block
module

^{1. Lua 5.4.7 liolib.c source file, including the definition of the cross-platform l}popen macro.

There seem to be no cross-platform way for that as of Lua-5.4.7 (2025).

As a work-around, on Linux and Mac:

for file in io.popen("ls -- /home/user"):lines() do
    print(file)
end

Or on Windows, something like:

for file in io.popen('dir "C:/something" /b'):lines() do
    print(file)
end

With this approach, you execute ls -- /home/user and read its output line by line.

You could use the io.popenfunction to run a OS command, in linux you can run ls -1 then get the output of the executed command.

local files = io.popen("ls -1")

the -1 is to list only the file names per line