Running out of space on your Ubuntu root directory (/) can lead to system performance issues and even prevent updates or installations. If your / directory is nearing its capacity, it’s time for some cleanup. Follow these steps to efficiently free up space on your Ubuntu system.

1. Identify Large Files and Directories

The first step is to find what’s taking up the most space.

sudo du -xh / | grep -P "^[0-9.]+G" | sort -hr | head -n 20

This command lists the top 20 largest files and directories. It gives you an idea of where to start.

2. Clear Package Cache

Package managers often leave behind cached files. Clean them up with:

sudo apt-get clean
sudo apt-get autoremove

3. Remove Old Kernels

Old kernels can occupy significant space. List installed kernels:

dpkg --list 'linux-image*'

Remove the old ones, ensuring not to remove the current kernel:

sudo apt-get remove --purge linux-image-<old-kernel-version>

4. Clear System Logs

System logs can grow large over time. Limit them to the last few days:

sudo journalctl --vacuum-time=3d

5. Remove Unused Packages

Identify and remove orphaned packages using deborphan:

sudo apt-get install deborphan
sudo deborphan | xargs sudo apt-get -y remove --purge

6. Check for Large Files

Search for large files manually:

sudo find / -type f -size +100M -exec ls -lh {} \\;

Review and delete unnecessary files.

7. Clean Temporary Files

Clear out temporary files:

sudo rm -rf /tmp/*
sudo rm -rf /var/tmp/*

8. Examine Disk Usage with ncdu

Use ncdu to interactively check disk usage:

sudo apt-get install ncdu
sudo ncdu /

This tool helps you navigate and identify large directories.

9. Manual Inspection

Check specific directories known for accumulating files:

sudo ls -lh /var/log
sudo ls -lh /var/cache

Manually remove unnecessary files.

10. Manage Snap Packages

Snap packages can also take up space. List and clean up old revisions:

sudo snap list --all
sudo snap remove <old-snap-revision>