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🚨 One filename change. Zero errors. Production broken.

A small Git detail taught me a production-level lesson the hard way.

I recently ran into a subtle issue while working with Git on Windows. It looked harmless at first — until it showed up in production.

I had a file named DEV.html. I pushed it to GitHub and everything worked as expected.

Later, I renamed it locally to dev.html (just a case change) and pushed again. No errors. No warnings. Everything looked fine.

But in production, links like <a href="dev.html"> started returning 404 – Page Not Found.

After some digging, I realized GitHub still had the file named DEV.html.

🔍 What was happening? This isn’t a Git bug, but a cross-platform design limitation:

Windows filesystems are case-insensitive
Git on Windows doesn’t detect case-only renames
GitHub runs on Linux, which is case-sensitive

So Git never recorded the rename, and GitHub never received it.

⚠️ Why this matters

In small projects, this is easy to miss. In larger projects, it can silently break navigation and cause production-only bugs — the classic “works on my machine” problem.

✅ What I learned

Always use lowercase filenames
Use git mv when renaming files
Enforce naming rules with CI or pre-commit hooks

Sharing this in case it helps someone avoid a similar issue.

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Can I run Apache and Nginx on the same AWS EC2 instance?

Yes ✅ you can install another web server like Nginx, but there is one important rule you must understand first.

1️⃣ Can multiple web servers be installed?

✔ YES — installed

❌ NO — running on the same port (by default)

You can install:

httpd (Apache)
nginx

at the same time.

But you cannot run both on port 80 at the same time.

2️⃣ Why port 80 is the problem

By default:

Apache (httpd) → listens on port 80
Nginx → listens on port 80

Only one process can bind to a port.

So:

One will start ✅
The other will fail ❌

3️⃣ Check if Apache is currently running

sudo systemctl status httpd

If you see:

Active: active (running)

👉 Apache is running on port 80.

4️⃣ You can safely install Nginx now

Installing does not affect Apache.

sudo yum install nginx -y

This only:

Downloads packages
Installs files
Does NOT start nginx automatically

5️⃣ What happens if you start Nginx now?

If Apache is running:

sudo systemctl start nginx

You’ll likely see:

Failed to start nginx.service: Address already in use

This is normal, not an error in installation.

6️⃣ Two safe ways to use both web servers

✅ Option 1: Stop Apache, use Nginx

sudo systemctl stop httpd
sudo systemctl disable httpd

Then:

sudo systemctl start nginx
sudo systemctl enable nginx

👉 Now Nginx uses port 80.

✅ Option 2: Run both using different ports (Learning setup)

Change Nginx port to 8080.

sudo vi /etc/nginx/nginx.conf

Change:

listen       80;

To:

listen       8080;

Then:

sudo systemctl start nginx

Access:

http://<EC2-IP>:8080

7️⃣ Check which service is using port 80

Very important command:

sudo ss -tulnp | grep :80

sudo lsof -i :80

This tells you exactly which process is using the port.

8️⃣ Why would someone install both?

Common real-world reasons:

Learning & comparison
Migrating from Apache → Nginx
Apache for legacy apps, Nginx as reverse proxy
Load balancing setup

9️⃣ AWS EC2 security group reminder ⚠️

Make sure:

Port 80 is allowed (HTTP)
Port 8080 is allowed (if used)

Security Group → Inbound rules

✅ Final Answer (Simple)

✔ You can install Nginx even if Apache exists ✔ You cannot run both on port 80 ✔ Stop one OR change port ✔ This is normal Linux behavior