# **Remove Unused Kernels**

05 May 2025 -  
**2 mins read time**

Tags:

[linux](/content/blog/tags#linux/index.html) [debian](/content/blog/tags#debian/index.html)

### 🔍 Step 1: Check What’s Using Space

Run this in your terminal:

```
sudo du -h --max-depth=1 / | sort -hr | head -n 10
```

This shows the largest directories in root. Investigate the biggest ones (like `/var`, `/usr`, `/home`, etc.).

* * *

### 🧹 Step 2: Clean Package Cache

```
sudo apt clean
```

This removes cached `.deb` files in `/var/cache/apt/archives`, which can take up a lot of space.

* * *

### 🧹 Step 3: Remove Unused Kernels

Check your current kernel:

```
uname -r
```

List installed kernels:

```
dpkg --list | grep linux-image
```

Remove old kernels (except the current one):

```
sudo apt remove --purge linux-image-X.X.X-XX-generic
# sudo apt remove --purge linux-image-6.1.0-33-amd64
# sudo apt purge linux-image-6.1.0-32-amd64
```

Be very careful not to remove the current or only working kernel.

* * *

### 🧹 Step 4: Remove Orphaned Packages

```
sudo apt autoremove
```

This removes packages installed as dependencies but no longer needed.

* * *

### 🧹 Step 5: Clean Journal Logs (if using `systemd`)

```
sudo journalctl --vacuum-time=3d
```

This deletes logs older than 3 days (adjust as needed).

* * *

### 🧼 Step 6: Identify & Delete Large Files

Find files larger than 100MB:

```
sudo find / -type f -size +100M -exec ls -lh {} \; 2>/dev/null | sort -k 5 -rh | head -n 20
```

Check if any are safe to delete (e.g., large ISO files, crash dumps, logs, etc.).

* * *

### 🧭 Optional: Move Files Off Root

If `/home` or an external drive has space:

```
sudo mv /path/to/large/file /home/youruser/
```

Or compress rarely used files:

```
gzip /path/to/large/file
```

* * *

### 🚨 Reboot After Cleaning

Once you’ve freed a few GB, reboot to ensure system services restart normally:

```
sudo reboot
```

After you’ve removed the old kernels and run `sudo apt autoremove`, you can check how much space is now free on your root partition with:

```
df -h /
```

This will output something like:

```
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2        20G   18G  1.5G  93% /
```

Look at the **“Avail”** column — it shows how much space is now free on your `/` partition.