Understanding Why Lua Worked in One Folder but Not Another on Windows (A Beginner's Learning Journey)

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June 9, 2026 at 3:15 am #6855
Rajeev Bagra
Keymaster
Many beginners assume that once a programming language has been downloaded and extracted, they can run it from anywhere on their computer. However, during the process of setting up Lua on Windows, an important issue emerged that taught valuable lessons about directories, executable files, and how Windows locates programs.

This learning post documents that experience and explains the concepts involved.

The Goal

The objective was to install Lua and begin experimenting with simple programs from Programming in Lua, starting with:
```
print("hello world")
```
Before that could happen, Lua needed to be launched successfully from Command Prompt.

The Starting Point

Lua had already been downloaded and extracted.

The extracted folder contained:
```
lua55.exe
luac55.exe
lua55.dll
wlua55.exe
```
Initially these files were located in:
```
C:\Users\SDM\Downloads\lua-5.5.0_Win32_bin
```
Later they were copied to:
```
C:\Users\SDM\Desktop
```
to make access easier.

Issue #1: Lua Was Installed but Would Not Run

After opening Command Prompt, the following command was entered:
```
lua5.5
```
Windows responded:
```
'lua5.5' is not recognized as an internal or external command,
operable program or batch file.
```
This is one of the most common errors encountered by Windows users.

Understanding the Error

The problem was not that Lua was broken.

The problem was that Windows could not find a program named:
```
lua5.5
```
The actual executable file was named:
```
lua55.exe
```
Notice the difference:
```
Incorrect: lua5.5
Correct:   lua55
```
Windows requires the exact executable name.

Issue #2: Being in the Wrong Directory

Another issue appeared when Command Prompt opened at:
```
C:\>
```
instead of:
```
C:\Users\SDM\Downloads\lua-5.5.0_Win32_bin>
```
At that moment Windows could not locate:
```
lua55.exe
```
because it was searching in the current directory.

Understanding the Current Directory

Think of Command Prompt as standing inside a folder.

If Command Prompt shows:
```
C:\>
```
it is currently standing in:
```
C:\
```
Windows automatically searches for executable files in the current location.

If Lua is stored elsewhere, Windows cannot find it.

The Solution: Change Directory

The following command was used:
```
cd \Users\SDM\Downloads\lua-5.5.0_Win32_bin
```
The prompt changed to:
```
C:\Users\SDM\Downloads\lua-5.5.0_Win32_bin>
```
Now Windows was standing inside the folder that contained Lua.

Successfully Launching Lua

Once inside the correct directory:
```
lua55
```
produced:
```
Lua 5.5.0 Copyright (C) 1994-2025 Lua.org, PUC-Rio
>
```
The symbol:
```
>
```
is Lua’s interactive prompt.

It indicates that Lua is ready to execute commands.

Making Things Easier: Moving Lua to the Desktop

To avoid repeatedly navigating into the Downloads folder, the Lua files were copied to:
```
C:\Users\SDM\Desktop
```
The Desktop now contained:
```
lua55.exe
luac55.exe
lua55.dll
wlua55.exe
```
This simplified access considerably.

Issue #3: How Do You Open Command Prompt in a Specific Folder?

Many beginners know how to open Command Prompt but do not know how to open it in the exact folder they need.

The solution was surprisingly simple.

Opening Command Prompt from File Explorer

While viewing the Desktop folder in File Explorer:
1. Click the address bar.
2. Type:
```
cmd
```
1. Press Enter.
Windows automatically opened Command Prompt in that location.

The prompt displayed:
```
C:\Users\SDM\Desktop>
```
This meant Command Prompt was already standing in the folder containing Lua.

Why This Trick Is Useful

Without this technique, users often have to type:
```
cd foldername
```
multiple times.

Using:
```
cmd
```
inside File Explorer immediately opens Command Prompt in the correct location.

This saves time and reduces mistakes.

Successfully Launching Lua from the Desktop

Because Command Prompt opened in:
```
C:\Users\SDM\Desktop>
```
the command:
```
lua55
```
worked immediately.

Output:
```
Lua 5.5.0 Copyright (C) 1994-2025 Lua.org, PUC-Rio
>
```
No additional navigation was required.

First Successful Lua Program

At the Lua prompt:
```
print("hello world")
```
Output:
```
hello world
```
Success!

The Lua interpreter was now working correctly.

Understanding Interactive Interpreters

Lua executes commands immediately.

For example:
```
print(2 + 3)
```
Output:
```
5
```
This allows experimentation without creating files.

Python behaves similarly:
```
>>> print("hello world")
hello world
```
Lua:
```
> print("hello world")
hello world
```
Lessons Learned

This stage of the setup process taught several valuable concepts.

1. Executable Names Matter

Windows requires exact program names.
```
lua55
```
works.
```
lua5.5
```
does not.

2. Current Directory Matters

Windows searches the current folder for executable programs.

If the executable is elsewhere, it may not be found.

3. The cd Command Changes Location
```
cd foldername
```
moves Command Prompt into another folder.

4. File Explorer Can Launch Command Prompt

Typing:
```
cmd
```
into the File Explorer address bar is one of the easiest ways to open Command Prompt in a specific folder.

5. Interactive Programming Is Powerful

The Lua prompt:
```
>
```
allows immediate experimentation and learning.

Final Success State

The final working environment looked like:
```
C:\Users\SDM\Desktop>lua55

Lua 5.5.0 Copyright (C) 1994-2025 Lua.org, PUC-Rio
>
```
And the first successful Lua program was:
```
print("hello world")
```
which produced:
```
hello world
```
At this point, the installation and setup phase was complete. The focus could now shift from troubleshooting Windows commands to learning Lua itself—variables, functions, recursion, tables, modules, and real-world programming projects. 🚀
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