# Mastering Disk Usage Analysis With ncdu

As a systems engineer, understanding disk usage is not just beneficial — it's essential for maintaining the health and performance of your servers. In this guide, we’ll explore how to efficiently analyze your filesystem using `ncdu` along with a few other reliable command-line tools.

## What is `ncdu`?

`ncdu` (NCurses Disk Usage) is a lightweight, interactive disk usage analyzer.  
It gives you a fast and easy way to identify which directories and files are hogging your disk space — all through a simple terminal interface.

## Installing `ncdu`

Getting `ncdu` up and running is quick:

**On Debian/Ubuntu-based systems:**

```bash
sudo apt install ncdu
```

**On Red Hat/CentOS/Fedora systems:**

```bash
sudo yum install ncdu
```

## Using `ncdu` to Analyze Filesystem Usage

Running `ncdu` is super straightforward — just point it at a directory:

```bash
ncdu /path/to/directory
```

### Restricting to a Single Filesystem

One of `ncdu`'s killer features is the `-x` option, which restricts the scan to a single filesystem:

```bash
ncdu -x /var/log
```

This is really handy when you want to avoid crossing into mounted volumes or other partitions accidentally.

### Navigating the `ncdu` Interface

When you launch `ncdu`, you can interact with it using your keyboard:

* Arrow keys: Navigate through the directories
    
* Enter: Dive into a directory
    
* `d`: Delete a file or directory (⚠️ use carefully)
    
* `q`: Quit the program
    

It’s intuitive enough that you’ll be flying through your filesystem in minutes.

## Alternative Tools for Disk Usage Analysis

While `ncdu` is amazing for interactive exploration, the good old command line has some other tricks up its sleeve.

### 1\. `df` — Display Free Disk Space

The `df` command shows you disk space usage and free space across all mounted filesystems:

```bash
df -h
```

The `-h` flag makes it human-readable (i.e., shows sizes in KB, MB, GB).

To focus on a specific directory:

```bash
df -h /var
```

### 2\. `du` — Estimate File and Directory Sizes

The `du` command is perfect for quick checks:

```bash
du -sh /var/log
```

* `-s`: Display only the total size
    
* `-h`: Human-readable format
    

Want a breakdown of subdirectories?

```bash
du -h --max-depth=1 /var/log | sort -hr
```

This will show you the size of each immediate subdirectory, sorted from largest to smallest.

### 3\. `find` — Locate Large Files

Sometimes you just need to hunt down the big files:

```bash
find /var -type f -size +100M -exec ls -lh {} \; | sort -k5 -hr
```

This finds files larger than 100MB and lists them, sorted by size.

## When to Use Each Tool

| **Tool** | **Best Use Case** |
| --- | --- |
| `ncdu` | Interactive exploration and cleanup |
| `df` | Quick snapshot of disk space across filesystems |
| `du` | Detailed file/directory size summaries (great for scripting) |
| `find` | Laser-targeted search for huge files |

## Conclusion

Keeping an eye on your disk usage is essential for any serious server management strategy.  
`ncdu` is an awesome tool for interactive, detailed analysis — especially when paired with options like `-x` to stay within boundaries.  
But don't sleep on the classics either: `df`, `du`, and `find` each bring their own strengths to your sysadmin toolkit.

By combining these tools, you’ll stay ahead of disk space problems before they turn into full-blown outages. 🚀